ABCD rating      A staging system for prostate cancer that uses ABCD. “A” and “B” refer to cancer that is confined to the prostate. “C” refers to cancer that has grown out of the prostate but has not spread to lymph nodes or other places in the body. “D” refers to cancer that has spread to lymph nodes or to other places in the body. Also called the Jewett staging system or the Whitmore-Jewett staging system.

ablation      In medicine, the removal or destruction of a body part or tissue or its function. Ablation may be performed by surgery, hormones, drugs, radiofrequency, heat, or other methods.

abscess      An enclosed collection of pus in tissues, organs, or confined spaces in the body. An abscess is a sign of infection and is usually swollen and inflamed.

action study      In cancer prevention clinical trials, a study that focuses on finding out whether actions people take can prevent cancer.

acute      Symptoms or signs that begin and worsen quickly; not chronic. 

acute lymphoblastic leukemia  (lim-fo-BLAST-ik loo-KEE-mee-a)    ALL. A quickly progressing disease in which too many immature white blood cells (called lymphoblasts) are found in the blood and bone marrow. Also called acute lymphocytic leukemia.

acute lymphocytic leukemia  (lim-fo-SIT-ik loo-KEE-mee-a)    ALL. A quickly progressing disease in which too many immature white blood cells (called lymphoblasts) are found in the blood and bone marrow. Also called acute lymphoblastic leukemia.

acute myelogenous leukemia  (mye-eh-LAH-jen-us loo-KEE-mee-a)    AML. A quickly progressing disease in which too many immature white blood cells (not lymphocytes) are found in the blood and bone marrow. Also called acute myeloid leukemia or acute nonlymphocytic leukemia.

acute myeloid leukemia  (MY-eh-loyd loo-KEE-mee-a)    AML. A quickly progressing disease in which too many immature white blood cells (not lymphocytes) are found in the blood and bone marrow. Also called acute myelogenous leukemia or acute nonlymphocytic leukemia.

acute nonlymphocytic leukemia      A quickly progressing disease in which too many immature blood-forming cells are found in the blood and bone marrow. Also called acute myeloid leukemia or acute myelogenous leukemia.

adenocarcinoma  (AD-in-o-kar-sin-O-ma)    Cancer that begins in cells that line certain internal organs and that have glandular (secretory) properties. 

adjunct agent      In cancer therapy, a drug or substance used in addition to the primary therapy.

adjunctive therapy      Another treatment used together with the primary treatment. Its purpose is to assist the primary treatment.

adjuvant therapy  (AD-joo-vant)    Treatment given after the primary treatment to increase the chances of a cure. Adjuvant therapy may include chemotherapy, radiation therapy, hormone therapy, or biological therapy.

adverse effect      An unwanted side effect of treatment.

agent study      In cancer prevention clinical trials, a study that tests whether taking certain medicines, vitamins, minerals, or food supplements can prevent cancer. Also a called chemoprevention study.

aggressive      A quickly growing cancer.

agranulocyte  (A-gran-yoo-lo-SITE)    A type of white blood cell; monocytes and lymphocytes are agranulocytes.

AJCC staging system      A system developed by the American Joint Committee on Cancer for describing the extent of cancer in a patient’s body. The descriptions include TNM: T describes the size of the tumor and if it has invaded nearby tissue, N describes any lymph nodes that are involved, and M describes metastasis (spread of cancer from one body part to another).

alkaloid      A member of a large group of chemicals that are made by plants and have nitrogen in them.

alkylating agent      A drug that is used in the treatment of cancer. It interferes with the cell's DNA and inhibits cell growth.

ALL      Acute lymphoblastic leukemia. A quickly progressing disease in which too many immature white blood cells called lymphoblasts are found in the blood and bone marrow. Also called acute lymphocytic leukemia.

all-trans retinoic acid      A form of vitamin A that is used in the treatment of acne. It is also being studied in cancer prevention and as a treatment for acute promyelocytic leukemia, usually in combination with other drugs. Also called tretinoin. 

allogeneic  (Al-o-jen-AY-ik)    Taken from different individuals of the same species. Also called allogenic.

allogeneic bone marrow transplantation  (AL-o-jen-AY-ik)    A procedure in which a person receives stem cells (cells from which all blood cells develop) from a genetically similar, but not identical, donor.

allogeneic stem cell transplantation  (AL-o-jen-AY-ik)    A procedure in which a person receives stem cells (cells from which all blood cells develop) from a genetically similar, but not identical, donor. 

allogenic      Taken from different individuals of the same species. Also called allogeneic.

alpha-fetoprotein  (AL-fa-FEE-toe-PRO-teen)    AFP. A protein normally produced by a fetus. AFP levels are usually undetectable in the blood of healthy adult men or women (who are not pregnant). An elevated level of AFP suggests the presence of either a primary liver cancer or germ cell tumor.

AML      Acute myelogenous leukemia. A quickly progressing disease in which too many immature blood-forming cells are found in the blood and bone marrow. Also called acute myeloid leukemia or acute nonlymphocytic leukemia.

analgesic      A drug that reduces pain. Analgesics include aspirin, acetaminophen, and ibuprofen.

analog      In chemistry, a substance that is similar, but not identical, to another. 

anaphylactic shock      A severe and sometimes life-threatening immune system reaction to an antigen that a person has been previously exposed to. The reaction may include itchy skin, edema, collapsed blood vessels, fainting, and difficulty in breathing.

anaplastic  (an-ah-PLAS-tik)    A term used to describe cancer cells that divide rapidly and have little or no resemblance to normal cells.

androgen  (AN-dro-jen)    A type of hormone that promotes the development and maintenance of male sex characteristics.

androgen ablation      Treatment to suppress or block the production of male hormones. Androgen suppression is achieved by surgical removal of the testicles, by taking female sex hormones, or by taking other drugs (antiandrogens). Also called androgen suppression.

androgen suppression      Treatment to suppress or block the production of male hormones. Androgen suppression is achieved by surgical removal of the testicles, by taking female sex hormones, or by taking other drugs, antiandrogens. Also called androgen ablation.

androgen-independent      Describes the ability of tumor cells to grow in the absence of androgens (hormones that promote the development and maintenance of male sex characteristics). Many early prostate cancers require androgens for growth, but advanced prostate cancers are often androgen-independent.

anemia  (a-NEE-mee-a)    A condition in which the number of red blood cells is below normal.

anesthesia  (an-es-THEE-zha)    Drugs or substances that cause loss of feeling or awareness. Local anesthetics cause loss of feeling in a part of the body. General anesthetics put the person to sleep.

anesthesiologist      A doctor who specializes in giving drugs or other agents to prevent or relieve pain during surgery or other procedures being done in the hospital.

anesthetic  (an-es-THET-ik)    A substance that causes loss of feeling or awareness. Local anesthetics cause loss of feeling in a part of the body. General anesthetics put the person to sleep.

angiogenesis  (an-gee-o-GEN-eh-sis)    Blood vessel formation. Tumor angiogenesis is the growth of blood vessels from surrounding tissue to a solid tumor. This is caused by the release of chemicals by the tumor.

angiogenesis inhibitor      A substance that may prevent the formation of blood vessels. In anticancer therapy, an angiogenesis inhibitor prevents the growth of blood vessels from surrounding tissue to a solid tumor.

angiostatin      A protein normally made by the body. It can also be made in the laboratory, and is being studied in the treatment of cancer. Angiostatin may prevent the growth of new blood vessels from the surrounding tissue to a solid tumor. It belongs to the family of drugs called angiogenesis inhibitors.

antiangiogenesis      Prevention of the growth of new blood vessels.

antibiotic  (an-tih-by-AH-tik)    A drug used to treat infections caused by bacteria and other microorganisms.

antibody  (AN-tih-BOD-ee)    A type of protein made by certain white blood cells in response to a foreign substance (antigen). Each antibody can bind to only a specific antigen. The purpose of this binding is to help destroy the antigen. Antibodies can work in several ways, depending on the nature of the antigen. Some antibodies destroy antigens directly. Others make it easier for white blood cells to destroy the antigen.

antibody therapy      Treatment with an antibody, a substance that can directly kill specific tumor cells or stimulate the immune system to kill tumor cells.

antiestrogen      A substance that blocks the activity of estrogens, the family of hormones that promote the development and maintenance of female sex characteristics.

antifolate      A substance that blocks the activity of folic acid. Antifolates are used to treat cancer. Also called folate antagonist.

antifungal      A drug that treats infections caused by fungi.

antigen      A substance that causes the immune system to make a specific immune response.

antigen-presenting cell      APC. A cell that shows antigen on its surface to other cells of the immune system. This is an important part of an immune response.

antigen-presenting cell vaccine      A vaccine made of antigens and antigen-presenting cells (APCs). Also called APC vaccine.

antihormone therapy      Treatment with drugs, surgery, or radiation in order to block the production or action of a hormone. Antihormone therapy may be used in cancer treatment because certain hormones are able to stimulate the growth of some types of tumors. 

antimetabolite      A drug that is very similar to natural chemicals in a normal biochemical reaction in cells but different enough to interfere with the normal division and functions of cells.

antimicrotubule agent      A drug that inhibits cell growth by stopping cell division. Antimicrotubule agents are used as treatments for cancer. Also called antimitotic agents, mitotic inhibitors, and taxanes. Docetaxel and paclitaxel are antimicrotubule agents.

antimitotic agent      A drug that inhibits cell growth by stopping cell division. Antimitotic agents are used as treatments for cancer. Also called antimicrotubule agents, mitotic inhibitors, and taxanes. Docetaxel and paclitaxel are antimitotic agents.

antineoplaston      A substance isolated from normal human blood and urine that is being tested as a type of treatment for some tumors and AIDS.

antiparasitic      A drug used to treat infections caused by bacteria and parasites. It is also used in the treatment of some cancers.

apheresis      A procedure in which blood is collected, part of the blood such as platelets or white blood cells is taken out, and the rest of the blood is returned to the donor. Also called pheresis.

apnea     cessation of breathing

apoptosis  (ap-o-TOE-sis)    A normal series of events in a cell that leads to its death.

arctigenin      A substance found in certain plants, including burdock. It has shown antiviral and anticancer effects. Arctigenin belongs to a group of substances called lignans.

arctiin      A substance found in certain plants, including burdock. It has shown anticancer effects. Arctiin belongs to a group of substances called lignans.

arginine butyrate      A substance that is being studied in the treatment of cancer.

aromatase inhibitor  (a-ROW-ma-tays in-HIB-it-er)    A drug that prevents the formation of estradiol, a female hormone, by interfering with an aromatase enzyme. Aromatase inhibitors are used as a type of hormone therapy for postmenopausal women who have hormone-dependent breast cancer.

arsenic      A poisonous chemical used to kill weeds and pests. Also used in cancer therapy.

arsenic trioxide      A substance that induces programmed cell death (apoptosis) in certain cancer cells. It belongs to the family of drugs called antineoplastics.

arterial embolization  (ar-TEE-ree-al EM-bo-lih-ZAY-shun)    The blocking of an artery by a clot of foreign material. This can be done as treatment to block the flow of blood to a tumor.

arthralgia    Pain in a joint.

asthenia   Loss or lack of bodily strength; weakness; debility.

astrocytoma  (as-troe-sye-TOE-ma)    A tumor that begins in the brain or spinal cord in small, star-shaped cells called astrocytes.

ataxia      Loss of muscle coordination.

ataxic gait  (ah-TAK-sik)    Awkward, uncoordinated walking.

athymic, nude mouse      A type of laboratory mouse that is hairless, lacks a normal thymus gland, and has a defective immune system because of a genetic mutation. Athymic, nude mice are often used in cancer research because they do not reject tumor cells, from mice or other species.

atypical teratoid/rhabdoid tumor      ATT/RHT or AT/RT. An aggressive cancer of the central nervous system, kidney, or liver that occurs in very young children.

autologous  (aw-TAHL-o-gus)    Taken from an individual's own tissues, cells, or DNA.

autologous bone marrow transplantation  (aw-TAHL-o-gus)    A procedure in which bone marrow is removed from a person, stored, and then given back to the person after intensive treatment.

autologous stem cell transplantation  (aw-TAHL-o-gus)    A procedure in which stem cells (cells from which all blood cells develop) are removed, stored, and then given back to the same person.

B cell      A white blood cell that makes antibodies and is an important part of the immune system. B cells come from bone marrow. Also called B lymphocyte.

B lymphocyte      A white blood cell that makes antibodies and is an important part of the immune system. B lymphocytes come from bone marrow. Also called B cell.

Bacillus Calmette Guérin  (bah-SILL-us KAL-met GAY-ran)    BCG. A type of bacteria used in cancer treatment to stimulate the immune system. It is also used to vaccinate against tuberculosis.

bacteremia    The presence of bacteria in the blood.

bacterial toxin      A toxic substance, made by bacteria, that can be modified to kill specific tumor cells without harming normal cells.

barium enema      A procedure in which a liquid with barium in it is put into the rectum and colon by way of the anus. Barium is a silver-white metallic compound that helps to show the image of the lower gastrointestinal tract on an x-ray.

barium solution      A liquid containing barium sulfate that is used in x-rays to highlight parts of the digestive system.

basal cell carcinoma  (BAY-sal sel kar-sin-O-ma)    A type of skin cancer that arises from the basal cells, small round cells found in the lower part (or base) of the epidermis, the outer layer of the skin.

benign  (beh-NINE)    Not cancerous. Benign tumors do not spread to tissues around them or to other parts of the body.

benign proliferative breast disease      A group of noncancerous conditions that may increase the risk of developing breast cancer. Examples include ductal hyperplasia, lobular hyperplasia, and papillomas.

benign prostatic hyperplasia  (hye-per-PLAY-zha)    BPH. A benign (noncancerous) condition in which an overgrowth of prostate tissue pushes against the urethra and the bladder, blocking the flow of urine. Also called benign prostatic hypertrophy.

benign prostatic hypertrophy      BPH. A benign (noncancerous) condition in which an overgrowth of prostate tissue pushes against the urethra and the bladder, blocking the flow of urine. Also called benign prostatic hyperplasia.

benign tumor  (beh-NINE)    A noncancerous growth that does not invade nearby tissue or spread to other parts of the body.

beta carotene      A vitamin A precursor. Beta carotene belongs to the family of fat-soluble vitamins called carotenoids.

beta-glucan      A type of polysaccharide (string of sugar molecules) obtained from several types of mushrooms. It is being studied as a treatment for cancer and as an immune system stimulant.

beta-human chorionic gonadotropin      ß-hCG. A hormone normally found in the blood and urine during pregnancy. It may also be produced by some tumor cells. An increased level of ß-hCG may be a sign of cancer of the testis, uterus, ovary, liver, stomach, pancreas, or lung. ß-hCG may also be produced in response to certain conditions that are not cancer. ß-hCG is being studied in the treatment of Kaposi’s sarcoma.

bias      In a clinical trial, a flaw in the study design or method of collecting or interpreting information. Biases can lead to incorrect conclusions about what the study or trial showed.

biological response modifier  (by-o-LAHJ-i-kul...)    BRM. Treatment to stimulate or restore the ability of the immune system to fight infections and other diseases. Also used to lessen side effects that may be caused by some cancer treatments. Also known as biological therapy, immunotherapy, or biotherapy.

biological therapy  (by-o-LAHJ-i-kul)    Treatment to stimulate or restore the ability of the immune system to fight infections and other diseases. Also used to lessen side effects that may be caused by some cancer treatments. Also known as immunotherapy, biotherapy, or biological response modifier (BRM) therapy.

biomarker      A substance sometimes found in the blood, other body fluids, or tissues. A high level of biomarker may mean that a certain type of cancer is in the body. Examples of biomarkers include CA 125 (ovarian cancer), CA 15-3 (breast cancer), CEA (ovarian, lung, breast, pancreas, and gastrointestinal tract cancers), and PSA (prostate cancer). Also called tumor marker.

biopsy  (BY-op-see)    The removal of cells or tissues for examination under a microscope. When only a sample of tissue is removed, the procedure is called an incisional biopsy or core biopsy. When an entire lump or suspicious area is removed, the procedure is called an excisional biopsy. When a sample of tissue or fluid is removed with a needle, the procedure is called a needle biopsy or fine-needle aspiration. 

biopsy specimen      Tissue removed from the body and examined under a microscope to determine whether disease is present.

biotherapy      Treatment to stimulate or restore the ability of the immune system to fight infections and other diseases. Also used to lessen side effects that may be caused by some cancer treatments. Also known as biological therapy, immunotherapy, or biological response modifier (BRM) therapy.

blast      An immature blood cell.

blessed thistle      Cnicus benedictus. A plant whose leaves, stems, and flowers have been used in some cultures to treat certain medical problems. Blessed thistle may have anti-inflammatory and anticancer effects. Also called St. Benedict's thistle, cardin, holy thistle, and spotted thistle.

blinded study      A type of study in which the patients (single-blinded) or the patients and their doctors (double-blinded) do not know which drug or treatment is being given. The opposite of a blinded study is an open label study.

blood cell count      A test to check the number of red blood cells, white blood cells, and platelets in a sample of blood. Also called complete blood count (CBC).

blood-brain barrier      A network of blood vessels with closely spaced cells that makes it difficult for potentially toxic substances (such as anticancer drugs) to penetrate the blood vessel walls and enter the brain.

blood-brain barrier disruption      BBBD. The use of drugs to create openings between cells in the blood-brain barrier. The blood-brain barrier is a protective network of blood vessels and tissue that protects the brain from harmful substances, but can also prevent anticancer drugs from reaching the brain. Once the barrier is opened, anticancer drugs may be infused into an artery that goes to the brain, in order to treat brain tumors. 

bolus      A single dose of drug usually injected into a blood vessel over a short period of time. Also called bolus infusion.

bone marrow      The soft, sponge-like tissue in the center of most large bones. It produces white blood cells, red blood cells, and platelets.

bone marrow ablation      The destruction of bone marrow using radiation or drugs.

bone marrow aspiration  (as-per-AY-shun)    The removal of a small sample of bone marrow (usually from the hip) through a needle for examination under a microscope.

bone marrow biopsy  (BY-op-see)    The removal of a sample of tissue from the bone marrow with a needle for examination under a microscope.

bone marrow metastases      Cancer that has spread from the original (primary) tumor to the bone marrow.

bone marrow transplantation  (trans-plan-TAY-shun)    A procedure to replace bone marrow that has been destroyed by treatment with high doses of anticancer drugs or radiation. Transplantation may be autologous (an individual's own marrow saved before treatment), allogeneic (marrow donated by someone else), or syngeneic (marrow donated by an identical twin).

bone metastases      Cancer that has spread from the original (primary) tumor to the bone.

bone scan      A technique to create images of bones on a computer screen or on film. A small amount of radioactive material is injected into a blood vessel and travels through the bloodstream; it collects in the bones and is detected by a scanner.

brachytherapy  (BRAKE-ih-THER-a-pee)    A procedure in which radioactive material sealed in needles, seeds, wires, or catheters is placed directly into or near a tumor. Also called internal radiation, implant radiation, or interstitial radiation therapy. 

bradycardia    Slowness of the heartbeat.

brain metastasis      Cancer that has spread from the original (primary) tumor to the brain.

brain stem      The part of the brain that is connected to the spinal cord.

brain stem glioma  (glee-O-ma)    A tumor located in the part of the brain that connects to the spinal cord (the brain stem). It may grow rapidly or slowly, depending on the grade of the tumor.

brain stem tumor      A tumor in the part of the brain that connects to the spinal cord (the brain stem).

breast cancer in situ      Abnormal cells that are confined to the ducts or lobules in the breast. There are two forms, called ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS).

breast duct endoscopy      A method used to examine the lining of the breast ducts to look for abnormal tissue. A very thin, flexible, lighted tube attached to a camera is inserted through the nipple, and threaded into the breast ducts deep in the breast. Tissue and fluid samples may be removed during the procedure. 

bronchoscope  (BRON-ko-skope)    A thin, lighted tube used to examine the inside of the trachea and bronchi, the air passages that lead to the lungs.

bronchoscopy  (bron-KOS-ko-pee)    A procedure in which a thin, lighted tube is inserted through the nose or mouth. This allows examination of the inside of the trachea and bronchi (air passages that lead to the lung), as well as the lung. Bronchoscopy may be used to detect cancer or to perform some treatment procedures.

bryostatin      A substance that is being studied in the treatment of cancer. It is obtained from a marine organism.

burdock      Arctium lappa. A plant whose seeds and root have been used in some cultures to treat certain medical problems. It may have antioxidant effects. Also called lappa and happy major.

Burkitt's lymphoma      An aggressive (rapidly progressing) type of B-cell non-Hodgkin's lymphoma that occurs most often in children and young adults. The disease may affect the jaw, central nervous system, bowel, kidneys, ovaries, or other organs. There are three main types of Burkitt’s lymphoma (sporadic, endemic, and immunodeficiency related). Sporadic Burkitt’s lymphoma occurs throughout the world, and endemic Burkitt’s lymphoma occurs in Africa. Immunodeficiency-related Burkitt’s lymphoma is most often seen in AIDS patients.

c-erbB-2      The gene that controls cell growth by making the human epidermal growth factor receptor 2. Also called HER2/neu.

CA 19-9 assay      A test that measures the level of CA 19-9 in the blood. CA 19-9 is a tumor marker released into the bloodstream from both cancer cells and normal cells. Higher than normal amounts of CA 19-9 in the blood can be a sign of gallbladder or pancreatic cancer or other conditions.

cachexia  (ka-KEK-see-a)    Loss of body weight and muscle mass, and weakness that may occur in patients with cancer, AIDS, or other chronic diseases.

cancer      A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread through the bloodstream and lymphatic system to other parts of the body. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the bloodstream. Lymphoma is cancer that begins in the cells of the immune system.

carcinogenesis      The process by which normal cells are transformed into cancer cells.

carcinoma  (KAR-si-NO-ma)    Cancer that begins in the skin or in tissues that line or cover internal organs.

carcinoma in situ  (KAR-si-NO-ma in SYE-too)    Cancer that involves only the cells in which it began and that has not spread to nearby tissues.

carcinosarcoma      A malignant tumor that is a mixture of carcinoma (cancer of epithelial tissue, which is skin and tissue that lines or covers the internal organs) and sarcoma (cancer of connective tissue, such as bone, cartilage, and fat).

carcinosis      A condition in which cancer is spread widely throughout the body, or, in some cases, to a relatively large region of the body. Also called carcinomatosis.

cardiotoxicity      Toxicity that affects the heart.

cardiovascular      Having to do with the heart and blood vessels.

carotenoid      A substance found in yellow and orange fruits and vegetables and in dark green, leafy vegetables. Carotenoids may reduce the risk of developing cancer.

case report      A detailed report of the diagnosis, treatment, and follow-up of an individual patient. Case reports also contain some demographic information about the patient (for example, age, gender, ethnic origin).

case series      A group or series of case reports involving patients who were given similar treatment. Reports of case series usually contain detailed information about the individual patients. This includes demographic information (for example, age, gender, ethnic origin) and information on diagnosis, treatment, response to treatment, and follow-up after treatment.

case-control study      A study that compares two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls). Researchers study the medical and lifestyle histories of the people in each group to learn what factors may be associated with the disease or condition. For example, one group may have been exposed to a particular substance that the other was not. Also called a retrospective study. 

CAT scan      A series of detailed pictures of areas inside the body, taken from different angles; the pictures are created by a computer linked to an x-ray machine. Also called computerized axial tomography, computed tomography (CT scan), or computerized tomography.

cauterization  (KAW-ter-ih-ZAY-shun)    The destruction of tissue with a hot instrument, an electrical current, or a caustic substance.

CBC      Complete blood count. A test to check the number of red blood cells, white blood cells, and platelets in a sample of blood. Also called blood cell count.

CEA      Carcinoembryonic antigen. A substance that is sometimes found in an increased amount in the blood of people who have certain cancers, other diseases, or who smoke. It is used as a tumor marker for colorectal cancer.

CEA assay      A laboratory test to measure carcinoembryonic antigen (CEA), a substance that is sometimes found in an increased amount in the blood of people who have certain cancers.

cell differentiation      The process during which young, immature (unspecialized) cells take on individual characteristics and reach their mature (specialized) form and function.

cell proliferation      An increase in the number of cells as a result of cell growth and cell division.

cellular adoptive immunotherapy      A treatment used to help the immune system fight cancer. A cancer patient’s T cells (a type of white blood cell) are collected and grown in the laboratory to increase the number of T cells that are able to kill the person’s cancer cells. These cancer-specific T cells are given back to the patient to help the immune system fight the cancer. 

central nervous system      CNS. The brain and spinal cord.

central nervous system primitive neuroectodermal tumor      CNS PNET. A type of cancer that arises from a particular type of cell within the brain or spinal cord.

cerebellopontine  (SER-uh-BEL-o-PON-teen)    Having to do with two structures of the brain, the cerebellum (located at the lower back of the brain) and the pons (located at the base of the brain in front of the cerebellum) and the area between them.

cerebellum  (ser-uh-BEL-um)    The portion of the brain in the back of the head between the cerebrum and the brain stem. The cerebellum controls balance for walking and standing, and other complex motor functions.

cerebral hemisphere  (seh-REE-bral HEM-is-feer)    One half of the cerebrum, the part of the brain that controls muscle functions and also controls speech, thought, emotions, reading, writing, and learning. The right hemisphere controls the muscles on the left side of the body, and the left hemisphere controls the muscles on the right side of the body.

cerebrospinal fluid  (seh-REE-broe-SPY-nal)    CSF. The fluid flowing around the brain and spinal cord. Cerebrospinal fluid is produced in the ventricles in the brain.

cerebrum  (seh-REE-brum)    The largest part of the brain. It is divided into two hemispheres, or halves, called the cerebral hemispheres. Areas within the cerebrum control muscle functions and also control speech, thought, emotions, reading, writing, and learning.

cervix  (SER-viks)    The lower, narrow end of the uterus that forms a canal between the uterus and vagina.

chemoembolization      A procedure in which the blood supply to the tumor is blocked surgically or mechanically and anticancer drugs are administered directly into the tumor. This permits a higher concentration of drug to be in contact with the tumor for a longer period of time.

chemoimmunotherapy      Chemotherapy combined with immunotherapy. Chemotherapy uses different drugs to kill or slow the growth of cancer cells; immunotherapy uses treatments to stimulate or restore the ability of the immune system to fight cancer. 

chemoradiation      Treatment that combines chemotherapy with radiation therapy. Also called chemoradiotherapy. 

chemotherapy  (kee-mo-THER-a-pee)    Treatment with anticancer drugs that are cytotoxic (toxic to cells).

Chinese rhubarb      Rheum palmatum or Rheum officinale. The root of this plant has been used in some cultures to treat certain medical problems. It may have anti-inflammatory and anticancer effects. Also called rhubarb, da-huang, Indian rhubarb, and Turkish rhubarb.

choroid plexus tumor      A rare type of cancer that occurs in the ventricles of the brain. It usually occurs in children younger than 2 years.

chromosome  (KRO-mo-some)    Part of a cell that contains genetic information. Except for sperm and eggs, all human cells contain 46 chromosomes.

chronic  (KRAHN-ik)    A disease or condition that persists or progresses over a long period of time.

clinical study      A type of research study that uses volunteers to test new methods of screening, prevention, diagnosis, or treatment of a disease. The trial may be carried out in a clinic or other medical facility. Also called a clinical trial. 

clinical trial      A type of research study that uses volunteers to test new methods of screening, prevention, diagnosis, or treatment of a disease. The trial may be carried out in a clinic or other medical facility. Also called a clinical study.

CNS      Central nervous system. The brain and spinal cord.

CNS metastasis      Cancer that has spread from the original (primary) tumor to the central nervous system.

CNS prophylaxis  (pro-fih-LAK-sis)    Chemotherapy or radiation therapy given to the central nervous system (CNS) as a preventive treatment. It is given to kill cancer cells that may be in the brain and spinal cord, even though no cancer has been detected there. Also called CNS sanctuary therapy. 

CNS tumor      A tumor of the central nervous system, including brain stem glioma, craniopharyngioma, medulloblastoma, and meningioma.

cobalt 60      A radioactive form of the metal cobalt, which is used as a source of radiation to treat cancer.

coenzyme Q10      A substance found in most tissues in the body, and in many foods. It can also be made in the laboratory. It is used by the body to produce energy for cells, and as an antioxidant. It is being studied in the treatment of cancer and in the relief of side effects caused by some cancer treatments. Also called Q10, CoQ10, vitamin Q10, and ubiquinone.

colon  (KO-lun)    The longest part of the large intestine, which is a tube-like organ connected to the small intestine at one end and the anus at the other. The colon removes water and some nutrients and electrolytes from partially digested food. The remaining material, solid waste called stool, moves through the colon to the rectum and leaves the body through the anus. 

colon cancer  (KO-lun)    Cancer that develops in the tissues of the colon.

colonoscopy  (ko-lun-AHS-ko-pee)    An examination of the inside of the colon using a thin, lighted tube (called a colonoscope) inserted into the rectum. If abnormal areas are seen, tissue can be removed and examined under a microscope to determine whether disease is present.

colony-stimulating factor      A substance that stimulates the production of blood cells. Colony-stimulating factors include granulocyte colony-stimulating factors (also called G-CSF and filgrastim), granulocyte-macrophage colony-stimulating factors (also called GM-CSF and sargramostim), and promegapoietin.

colorectal  (ko-lo-REK-tul)    Having to do with the colon or the rectum.

combination chemotherapy      Treatment using more than one chemotherapy drug.

comorbidity      The condition of having two or more diseases at the same time.

complete blood count      CBC. A test to check the number of red blood cells, white blood cells, and platelets in a sample of blood. Also called blood cell count.

complete hysterectomy      Surgery to remove the entire uterus, including the cervix. Sometimes, not all of the cervix is removed. Also called total hysterectomy.

complete metastasectomy  (meh-TAS-ta-SEC-tuh-mee)    Surgery to remove all metastases (tumors formed from cells that have spread from the primary tumor). 

complete remission      The disappearance of all signs of cancer in response to treatment. This does not always mean the cancer has been cured. Also called a complete response.

complete response      The disappearance of all signs of cancer in response to treatment. This does not always mean the cancer has been cured. Also called a complete remission.

computed tomographic colonography      CTC. A procedure in which a detailed picture of the colon is created by an x-ray machine linked to a computer. Also called computed tomography (CT) scan or computerized axial tomography (CAT) scan of the colon.

computed tomography  (tuh-MAH-gra-fee)    CT scan. A series of detailed pictures of areas inside the body taken from different angles; the pictures are created by a computer linked to an x-ray machine. Also called computerized tomography and computerized axial tomography (CAT) scan.

computerized axial tomography  (com-PYEW-ter-ized AX-ee-al tuh-MAH-gra-fee)    A series of detailed pictures of areas inside the body taken from different angles; the pictures are created by a computer linked to an x-ray machine. Also called CAT scan, computed tomography (CT scan), or computerized tomography.

computerized tomography      A series of detailed pictures of areas inside the body taken from different angles; the pictures are created by a computer linked to an x-ray machine. Also called computerized axial tomography (CAT) scan and computed tomography (CT scan).

concurrent therapy      A treatment that is given at the same time as another.

consecutive case series      A clinical study that includes all eligible patients identified by the researchers during the study registration period. The patients are treated in the order in which they are identified. This type of study usually does not have a control group. 

consolidation therapy      A type of high-dose chemotherapy often given as the second phase (after induction therapy) of a cancer treatment regimen for leukemia. Also called intensification therapy. 

control group      In a clinical trial, the group that does not receive the new treatment being studied. This group is compared to the group that receives the new treatment, to see if the new treatment works.

controlled clinical trial      A clinical study that includes a comparison (control) group. The comparison group receives a placebo, another treatment, or no treatment at all.

controlled study      An experiment or clinical trial that includes a comparison (control) group.

cooperative group      A group of physicians, hospitals, or both formed to treat a large number of persons in the same way so that a new treatment can be evaluated quickly. Clinical trials of new cancer treatments often require many more people than a single physician or hospital can care for.

CoQ10      A substance found in most tissues in the body, and in many foods. It can also be made in the laboratory. It is used by the body to produce energy for cells, and as an antioxidant. It is being studied in the treatment of cancer and in the relief of side effects caused by some cancer treatments. Also called coenzyme Q10, Q10, vitamin Q10, and ubiquinone.

craniotomy  (kray-nee-AH-toe-mee)    An operation in which an opening is made in the skull.

cruciferous vegetable      A member of the family of vegetables that includes kale, collard greens, broccoli, cauliflower, cabbage, Brussels sprouts, and turnips. These vegetables contain substances that may protect against cancer. 

cryopreservation      The process of cooling and storing cells, tissues, or organs at very low or freezing temperatures to save them for future use.

cryosurgery  (KRYE-o-SER-juh-ree)    Treatment performed with an instrument that freezes and destroys abnormal tissues.

cryotherapy      Any method that uses cold temperature to treat disease.

CSF      Cerebrospinal fluid. The fluid flowing around the brain and spinal cord. CSF is produced in the ventricles of the brain.

CT scan      Computed tomography scan. A series of detailed pictures of areas inside the body taken from different angles; the pictures are created by a computer linked to an x-ray machine. Also called computerized tomography and computerized axial tomography (CAT) scan.

cumulative dose      In medicine, the total amount of a drug or radiation given to a patient over time; for example, the total dose of radiation given in a series of radiation treatments.

cytology      The study of cells using a microscope.

cytotoxic      Cell-killing.

cytotoxic chemotherapy      Anticancer drugs that kill cells, especially cancer cells.

cytotoxic T cell        A type of white blood cell that can directly destroy specific cells. T cells can be separated from other blood cells, grown in the laboratory, and then given to a patient to destroy tumor cells. Certain cytokines can also be given to a patient to help form cytotoxic T cells in the patient's body.

da-huang      Rheum palmatum or Rheum officinale. The root of this plant has been used in some cultures to treat certain medical problems. It may have anti-inflammatory and anticancer effects. Also called rhubarb, Chinese rhubarb, Indian rhubarb, and Turkish rhubarb.

DCIS      Ductal carcinoma in situ. A noninvasive, precancerous condition in which abnormal cells are found in the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast. In some cases, DCIS may become invasive cancer and spread to other tissues, although it is not known at this time how to predict which lesions will become invasive. Also called intraductal carcinoma.

de novo  (dih NO-vo)    In cancer, the first occurrence of cancer in the body.

dendritic cell      A special type of antigen-presenting cell (APC) that activates T lymphocytes. 

dendritic cell vaccine      A vaccine made of antigens and dendritic antigen-presenting cells (APCs).

differentiation      In cancer, refers to how mature (developed) the cancer cells are in a tumor. Differentiated tumor cells resemble normal cells and tend to grow and spread at a slower rate than undifferentiated or poorly differentiated tumor cells, which lack the structure and function of normal cells and grow uncontrollably.

disease progression      Cancer that continues to grow or spread.

disease-free survival      Length of time after treatment during which no cancer is found. Can be reported for an individual patient or for a study population. 

disease-specific survival      The percentage of subjects in a study who have survived a particular disease for a defined period of time. Usually reported as time since diagnosis or treatment. In calculating this percentage, only deaths from the disease being studied are counted. Subjects who died from some other cause are not included in the calculation.

disseminate  (dih-SEM-ih-NATE)    Scatter or distribute over a large area or range.

DNA      Deoxyribonucleic acid. The molecules inside cells that carry genetic information and pass it from one generation to the next.

dose-limiting      Describes side effects of a drug or other treatment that are serious enough to prevent an increase in dose or level of that treatment.

dosimetrist  do-SIM-uh-trist    A person who determines the proper radiation dose for treatment.

double-blinded      A clinical trial in which neither the medical staff nor the person knows which of several possible therapies the person is receiving.

double-contrast barium enema      A procedure in which x-rays of the colon and rectum are taken after a liquid containing barium is put into the rectum. Barium is a silver-white metallic compound that outlines the colon and rectum on an x-ray and helps show abnormalities. Air is put into the rectum and colon to further enhance the x-ray.

ductal carcinoma in situ  (DUK-tal KAR-si-NO-ma in SYE-too)    DCIS. A noninvasive, precancerous condition in which abnormal cells are found in the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast. In some cases, ductal carcinoma in situ may become invasive cancer and spread to other tissues, although it is not known at this time how to predict which lesions will become invasive. Also called intraductal carcinoma.

Dukes' classification      A staging system used to describe the extent of colorectal cancer. Stages range from A (early stage) to D (advanced stage).

dysplasia  (dis-PLAY-zha)    Cells that look abnormal under a microscope but are not cancer.

dyspnea     Difficult or labored breathing.

EBV      Epstein-Barr virus. A common virus that remains dormant in most people. It has been associated with certain cancers, including Burkitt's lymphoma, immunoblastic lymphoma, and nasopharyngeal carcinoma.

edema  (eh-DEE-ma)    Swelling caused by excess fluid in body tissues.

efficacy      Effectiveness. In medicine, the ability of an intervention (for example, a drug or surgery) to produce the desired beneficial effect.

eligibility criteria      In clinical trials, requirements that must be met for an individual to be included in a study. These requirements help make sure that patients in a trial are similar to each other in terms of specific factors such as age, type and stage of cancer, general health, and previous treatment. When all participants meet the same eligibility criteria, it gives researchers greater confidence that results of the study are caused by the intervention being tested and not by other factors.

embolization  (EM-bo-lih-ZAY-shun)    The blocking of an artery by a clot or foreign material. Embolization can be done as treatment to block the flow of blood to a tumor.

embryonal tumor      A mass of rapidly growing cells that begins in embryonic (fetal) tissue. Embryonal tumors may be benign or malignant, and include neuroblastomas and Wilms’ tumors. Also called embryoma. 

emesis      Vomiting.

endocrine therapy      Treatment that adds, blocks or removes hormones. For certain conditions (such as diabetes or menopause), hormones are given to adjust low hormone levels. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body's natural hormones. Sometimes surgery is needed to remove the gland that makes hormones. Also called hormone therapy, hormonal therapy, or hormone treatment.

endoscopy  (en-DAHS-ko-pee)    The use of a thin, lighted tube (called an endoscope) to examine the inside of the body.

endpoint      In clinical trials, an event or outcome that can be measured objectively to determine whether the intervention being studied is beneficial. The endpoints of a clinical trial are usually included in the study objectives. Some examples of endpoints are survival, improvements in quality of life, relief of symptoms, and disappearance of the tumor.

enteritis    Inflammation of the intestines, applied chiefly to inflammation of the small intestines.

ependymoma  (ep-en-dih-MOE-mah)    A type of brain tumor that may arise in the ventricles of the brain or in the spinal cord. Also called an ependymal tumor.

epistaxis    Nosebleed.

Epstein-Barr virus      EBV. A common virus that remains dormant in most people. It has been associated with certain cancers, including Burkitt's lymphoma, immunoblastic lymphoma, and nasopharyngeal carcinoma.

ER      Estrogen receptor. Protein found on some cancer cells to which estrogen will attach.

ER+      Estrogen receptor positive. Breast cancer cells that have a protein (receptor molecule) to which estrogen will attach. Breast cancer cells that are ER+ need the hormone estrogen to grow and will usually respond to hormone (antiestrogen) therapy that blocks these receptor sites.

ER-      Estrogen receptor negative. Breast cancer cells that do not have a protein (receptor molecule) to which estrogen will attach. Breast cancer cells that are ER- do not need the hormone estrogen to grow and usually do not respond to hormone (antiestrogen) therapy that blocks these receptor sites.

ErbB1      Epidermal growth factor receptor. The protein found on the surface of some cells and to which epidermal growth factor binds, causing the cells to divide. It is found at abnormally high levels on the surface of many types of cancer cells, so these cells may divide excessively in the presence of epidermal growth factor. Also known as EGFR or HER1.

erythema      Redness of the skin.

erythrocyte  (eh-RITH-ro-site)    A cell that carries oxygen to all parts of the body. Also called a red blood cell (RBC).

erythrocyte sedimentation rate      ESR. The distance red blood cells travel in one hour in a sample of blood as they settle to the bottom of a test tube. The sedimentation rate is increased in inflammation, infection, cancer, rheumatic diseases, and diseases of the blood and bone marrow. Also called sedimentation rate. 

esophagitis    Inflammation of the esophagus.

estrogen receptor      ER. Protein found on some cancer cells to which estrogen will attach.

estrogen receptor negative      ER-. Breast cancer cells that do not have a protein (receptor molecule) to which estrogen will attach. Breast cancer cells that are ER- do not need the hormone estrogen to grow and usually do not respond to hormone (antiestrogen) therapy that blocks these receptor sites.

estrogen receptor positive      ER+. Breast cancer cells that have a protein (receptor molecule) to which estrogen will attach. Breast cancer cells that are ER+ need the hormone estrogen to grow and will usually respond to hormone (antiestrogen) therapy that blocks these receptor sites.

estrogen receptor test      A lab test to determine if breast cancer cells have estrogen receptors. If the cells have estrogen receptors, they may depend on estrogen for growth. This information may influence how the breast cancer is treated.

estrogen replacement therapy      ERT. Hormones (estrogen, progesterone, or both) given to postmenopausal women or to women who have had their ovaries surgically removed. Hormones are given to replace the estrogen no longer produced by the ovaries.

etiology      The cause or origin of disease.

evaluable disease      Disease that cannot be measured directly by the size of the tumor but can be evaluated by other methods specific to a particular clinical trial.

evaluable patients      Patients whose response to a treatment can be measured because enough information has been collected.

Ewing's sarcoma  (YOO-ingz sar-KO-ma)    A type of bone cancer that usually forms in the middle (shaft) of large bones. Also called Ewing's sarcoma/primitive neuroectodermal tumor (PNET).

extensive-stage small cell lung cancer      Cancer has spread outside of the lung in which it began or to other parts of the body. 

external radiation  (ray-dee-AY-shun)    Radiation therapy that uses a machine to aim high-energy rays at the cancer. Also called external-beam radiation.

external-beam radiation  (ray-dee-AY-shun)    Radiation therapy that uses a machine to aim high-energy rays at the cancer. Also called external radiation.

extravasation    A discharge or escape, as of blood, from a vessel into the tissues.

false-negative test result      A test result that indicates that a person does not have a specific disease or condition when the person actually does have the disease or condition.

false-positive test result      A test result that indicates that a person has a specific disease or condition when the person actually does not have the disease or condition.

fecal occult blood test  (FEE-kul o-KULT)    FOBT. A test to check for blood in stool. (Fecal refers to stool; occult means hidden.)

fibroblast      A connective tissue cell that makes and secretes collagen proteins.

fibroid  (FYE-broyd)    A benign smooth-muscle tumor, usually in the uterus or gastrointestinal tract. Also called leiomyoma.

filgrastim      A colony-stimulating factor that stimulates the production of neutrophils (a type of white blood cell). It is a cytokine that belongs to the family of drugs called hematopoietic (blood-forming) agents. Also called granulocyte colony-stimulating factor (G-CSF).

first-line therapy      The first type of therapy given for a condition or disease. 

flow cytometry      A method of measuring the number of cells in a sample, the percentage of live cells in a sample, and certain characteristics of cells, such as size, shape, and the presence of tumor markers on the cell surface. The cells are stained with a light-sensitive dye, placed in a fluid, and passed in a stream before a laser or other type of light. The measurements are based on how the light-sensitive dye reacts to the light. 

follicular mixed cell lymphoma  (fo-LIK-yu-ler mixed cell lim-FO-ma)    An indolent (slow-growing) type of B-cell non-Hodgkin's lymphoma (cancer of the lymphatic system) in which there are both small and large cancer cells.

fractionation      Dividing the total dose of radiation therapy into several smaller, equal doses delivered over a period of several days.

G-CSF      Granulocyte colony-stimulating factor. A colony-stimulating factor that stimulates the production of neutrophils (a type of white blood cell). It is a cytokine that belongs to the family of drugs called hematopoietic (blood-forming) agents. Also called filgrastim.

gamma irradiation      A type of radiation therapy that uses gamma radiation. Gamma radiation is a type of high-energy radiation that is different from x-rays.

gamma knife      Radiation therapy in which high-energy rays are aimed at a tumor from many angles in a single treatment session.

gastrointestinal tract  (GAS-tro-in-TES-tih-nul)    The stomach and intestines.

gene      The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.

gene therapy      Treatment that alters a gene. In studies of gene therapy for cancer, researchers are trying to improve the body's natural ability to fight the disease or to make the cancer cells more sensitive to other kinds of therapy.

gene transfer      The insertion of genetic material into a cell.

genetic markers      Alterations in DNA that may indicate an increased risk of developing a specific disease or disorder.

germ cell tumor      A type of tumor that begins in the cells that give rise to sperm or eggs. Germ cell tumors can occur almost anywhere in the body and can be either benign or malignant.

Gleason score  (GLEE-sun)    A system of grading prostate cancer cells based on how they look under a microscope. Gleason scores range from 2 to 10 and indicate how likely it is that a tumor will spread. A low Gleason score means the cancer cells are similar to normal prostate cells and are less likely to spread; a high Gleason score means the cancer cells are very different from normal and are more likely to spread.

glial cell  (GLEE-al)    A type of cell that surrounds nerve cells and holds them in place. Glial cells also insulate nerve cells from each other.

glial tumor      A general term for tumors of the central nervous system, including astrocytomas, ependymal tumors, glioblastoma multiforme, and primitive neuroectodermal tumors.

glioblastoma  (glee-o-blas-TOE-ma)    A general term that refers to malignant astrocytoma, a type of brain tumor.

glioblastoma multiforme  (glee-o-blas-TOE-ma mul-tih-FOR-may)    A type of brain tumor that forms from glial (supportive) tissue of the brain. It grows very quickly and has cells that look very different from normal cells. Also called grade IV astrocytoma.

glioma  (glee-O-ma)    A cancer of the brain that begins in glial cells (cells that surround and support nerve cells).

gliosarcoma      A type of glioma (cancer of the brain that comes from glial, or supportive, cells).

GM-CSF      Granulocyte-macrophage colony-stimulating factor. A colony-stimulating factor that stimulates the production of white blood cells, especially granulocytes and macrophages, and cells (in the bone marrow) that are precursors of platelets. It is a cytokine that belongs to the family of drugs called hematopoietic (blood-forming) agents. Also called sargramostim.

grade      The grade of a tumor depends on how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. Grading systems are different for each type of cancer. 

grade IV astrocytoma      A type of brain tumor that forms from glial (supportive) tissue of the brain. It grows very quickly and has cells that look very different from normal cells. Also called glioblastoma multiforme.

grading      A system for classifying cancer cells in terms of how abnormal they appear when examined under a microscope. The objective of a grading system is to provide information about the probable growth rate of the tumor and its tendency to spread. The systems used to grade tumors vary with each type of cancer. Grading plays a role in treatment decisions.

granulocyte  (GRAN-yoo-lo-site)    A type of white blood cell that fights bacterial infection. Neutrophils, eosinophils, and basophils are granulocytes.

granulocyte colony-stimulating factor      G-CSF. A colony-stimulating factor that stimulates the production of neutrophils (a type of white blood cell). It is a cytokine that belongs to the family of drugs called hematopoietic (blood-forming) agents. Also called filgrastim. 

hairy cell leukemia      A rare type of leukemia in which abnormal B-lymphocytes (a type of white blood cell) are present in the bone marrow, spleen, and peripheral blood. When viewed under a microscope, these cells appear to be covered with tiny hair-like projections.

hand-foot syndrome      A condition marked by pain, swelling, numbness, tingling, or redness of the hands or feet. It sometimes occurs as a side effect of certain anticancer drugs. Also known as palmar-plantar erythodysthesia.

Hedyotis diffusa      An herb used in traditional Chinese medicine to treat certain medical problems. It has been used to boost the immune system and may have anticancer effects.

Hematologic    Referring to blood and blood forming tissues.

hematologic malignancy      A cancer of the blood or bone marrow, such as leukemia or lymphoma. Also called hematologic cancer.

hematologist  (hee-ma-TOL-o-jist)    A doctor who specializes in treating blood disorders.

hematopoietic tissue      Tissue in which new blood cells are formed.

hemiperesis    Muscular weakness affecting one side of the body.

hemoglobin  (HE-muh-GLOW-bun)    The substance inside red blood cells that binds to oxygen and carries it from the lungs to the tissues.

hemorrhage      In medicine, loss of blood from damaged blood vessels. A hemorrhage may be internal or external, and usually involves a lot of bleeding in a short time. 

hepatectomy      Surgery to remove all or part of the liver.

hepatic      Refers to the liver.

hepatic arterial infusion      A procedure to deliver chemotherapy directly to the liver. Catheters are put into an artery in the groin that leads directly to the liver, and drugs are given through the catheters. 

hepatic artery      The major blood vessel that carries blood to the liver. 

hepatoblastoma  (HEP-a-toe-blas-TOE-ma)    A type of liver tumor that occurs in infants and children.

hepatocellular carcinoma  (HEP-a-toe-SEL-yoo-ler kar-sin-O-ma)    A type of adenocarcinoma, the most common type of liver tumor.

hepatocyte  (HEP-a-toe-site)    A liver cell.

hepatoma  (hep-a-TOE-ma)    A liver tumor.

HER1      Epidermal growth factor receptor. The protein found on the surface of some cells and to which epidermal growth factor binds, causing the cells to divide. It is found at abnormally high levels on the surface of many types of cancer cells, so these cells may divide excessively in the presence of epidermal growth factor. Also known as EGFR or ErbB1.

HER2/neu      Human epidermal growth factor receptor 2. The HER2/neu protein is involved in the growth of some cancer cells. Also called c-erbB-2. 

herba scutellaria barbatae      An herb used in traditional Chinese medicine to treat certain medical problems. It may have anticancer effects.

high grade      When referring to cancerous and precancerous growths, a term used to describe cells that look abnormal under a microscope. These cells are more likely to grow and spread quickly than cells in low-grade cancerous and precancerous growths.

high-dose chemotherapy      An intensive drug treatment to kill cancer cells, but that also destroys the bone marrow and can cause other severe side effects including death from sepsis (infection). High-dose chemotherapy is usually followed by bone marrow or stem cell transplantation to rebuild the bone marrow.

high-energy photon therapy      A type of radiation therapy that uses high-energy photons (units of light energy). High-energy photons penetrate deeply into tissues to reach tumors while giving less radiation to superficial tissues such as the skin. 

high-risk cancer      Cancer that is likely to recur (come back), or spread. 

histology      The study of tissues and cells under a microscope.

Hodgkin's disease      A malignant disease of the lymphatic system that is characterized by painless enlargement of lymph nodes, the spleen, or other lymphatic tissue. Other symptoms may include fever, weight loss, fatigue, or night sweats. Also called Hodgkin's lymphoma.

Hodgkin's lymphoma      A malignant disease of the lymphatic system that is characterized by painless enlargement of lymph nodes, the spleen, or other lymphatic tissue. Other symptoms may include fever, weight loss, fatigue, or night sweats. Also called Hodgkin's disease.

holy thistle      Cnicus benedictus. A plant whose leaves, stems, and flowers have been used in some cultures to treat certain medical problems. Holy thistle may have anti-inflammatory and anticancer effects. Also called blessed thistle, St. Benedict's thistle, cardin, and spotted thistle.

hormonal therapy      Treatment that adds, blocks or removes hormones. For certain conditions (such as diabetes or menopause), hormones are given to adjust low hormone levels. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body's natural hormones. Sometimes surgery is needed to remove the gland that makes hormones. Also called hormone therapy, hormone treatment, or endocrine therapy.

hormone receptor      A protein on the surface of a cell that binds to a specific hormone. The hormone causes many changes to take place in the cell. 

hormone replacement therapy      HRT. Hormones (estrogen, progesterone, or both) given to women after menopause to replace the hormones no longer produced by the ovaries. Also called menopausal hormone therapy.

hormone responsive      In oncology, describes cancer that responds to hormone treatment.

hormone therapy      Treatment that adds, blocks or removes hormones. For certain conditions (such as diabetes or menopause), hormones are given to adjust low hormone levels. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body's natural hormones. Sometimes surgery is needed to remove the gland that makes hormones. Also called hormonal therapy, hormone treatment, or endocrine therapy. 

hormone treatment      Treatment that adds, blocks or removes hormones. For certain conditions (such as diabetes or menopause), hormones are given to adjust low hormone levels. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body's natural hormones. Sometimes surgery is needed to remove the gland that makes hormones. Also called hormonal therapy, hormone therapy, or endocrine therapy. 

host cell      A cell that is infected by a virus or another type of microorganism.

HRT      Hormone replacement therapy. Hormones (estrogen, progesterone, or both) given to women after menopause to replace the hormones no longer produced by the ovaries. Also called menopausal hormone therapy.

HTLV-1      Human T-cell leukemia virus type 1. A retrovirus that infects T-cells (a type of white blood cell) and can cause leukemia and lymphoma. HTLV-1 is spread by sharing syringes or needles used to inject drugs, through sexual contact, and from mother to child at birth or through breast-feeding. 

human epidermal growth factor receptor 2      HER2/neu. The HER2/neu protein is involved in growth of some cancer cells. Also called c-erbB-2. 

human T-cell leukemia virus type 1      A retrovirus that infects T-cells (a type of white blood cell) and can cause leukemia and lymphoma. HTLV-1 is spread by sharing syringes or needles used to inject drugs, through sexual contact, and from mother to child at birth or through breast-feeding. 

hydrazine sulfate      A substance that has been studied as a treatment for cancer and as a treatment for cachexia (body wasting) associated with advanced cancer.

hydrocephalus  (hye-dro-SEF-uh-lus)    The abnormal buildup of cerebrospinal fluid in the ventricles of the brain.

hyperbaric oxygen      Oxygen that is at an atmospheric pressure higher than the pressure at sea level. Breathing hyperbaric oxygen to enhance the effectiveness of radiation therapy is being studied.

hypercalcemia  (hye-per-kal-SEE-mee-a)    Abnormally high blood calcium.

hyperfractionation      A way of giving radiation therapy in smaller-than-usual doses two or three times a day instead of once a day.

hyperglycemia      Abnormally high blood sugar.

hypernephroma  (HYE-per-neh-FRO-ma)    The most common type of kidney cancer. It begins in the lining of the renal tubules in the kidney. The renal tubules filter the blood and produce urine. Also called renal cell cancer. 

hyperplasia  (hye-per-PLAY-zha)    An abnormal increase in the number of cells in an organ or tissue.

hyperthermia therapy  (hye-per-THER-mee-a)    A type of treatment in which body tissue is exposed to high temperatures to damage and kill cancer cells or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs.

hyperuricemia      A buildup of uric acid (a byproduct of metabolism) in the blood; a side effect of some anticancer drugs.

hyponatremia    Deficiency of sodium in the blood.

idiopathic      Describes a disease of unknown cause.

ileostomy  (il-ee-AHS-toe-mee)    An opening into the ileum, part of the small intestine, from the outside of the body. An ileostomy provides a new path for waste material to leave the body after part of the intestine has been removed.

ileus    Obstruction of the intestines.

IM      Intramuscular. Within or into muscle.

immune response      The activity of the immune system against foreign substances (antigens).

immune system  (im-YOON)    The complex group of organs and cells that defends the body against infections and other diseases.

immunocompetent      Having the ability to produce a normal immune response.

immunocompromised      Having a weakened immune system caused by certain diseases or treatments.

immunodeficiency      The decreased ability of the body to fight infection and disease.

immunotherapy  (IM-yoo-no-THER-a-pee)    Treatment to stimulate or restore the ability of the immune system to fight infections and other diseases. Also used to lessen side effects that may be caused by some cancer treatments. Also known as biological therapy, biotherapy, or biological response modifier (BRM) therapy.

immunotoxin      An antibody linked to a toxic substance. Some immunotoxins can bind to cancer cells and kill them.

implant radiation  (ray-dee-AY-shun)    A procedure in which radioactive material sealed in needles, seeds, wires, or catheters is placed directly into or near a tumor. Also called brachytherapy, internal radiation, or interstitial radiation.

implantable pump      A small device installed under the skin to administer a steady dose of drugs.

in situ cancer      Early cancer that has not spread to neighboring tissue.

incidence      The number of new cases of a disease diagnosed each year.

incisional biopsy  (in-SIH-zhun-al BY-op-see)    A surgical procedure in which a portion of a lump or suspicious area is removed for diagnosis. The tissue is then examined under a microscope.

Indian cress      Nasturtium officinale. Parts of the flowering plant have been used in some cultures to treat certain medical problems. It may have anticancer effects. Also called watercress.

Indian elm      Ulmus fulva or Ulmus rubra. The inner bark of this plant has been used in some cultures to treat certain medical problems. It may have antioxidant effects. Also called slippery elm, gray elm, red elm, and sweet elm.

Indian rhubarb      Rheum palmatum or Rheum officinale. The root of this plant has been used in some cultures to treat certain medical problems. It may have anti-inflammatory and anticancer effects. Also called rhubarb, da-huang, Chinese rhubarb, and Turkish rhubarb.

Indian valerian      Valeriana officinalis. A plant whose roots are used as a sedative and to treat certain medical conditions. It is being studied as a way to improve sleep in cancer patients undergoing treatment. Also called valerian, garden valerian, Pacific valerian, Mexican valerian, garden heliotrope, and Valerianae radix. 

indolent  (IN-doe-lint)    A type of cancer that grows slowly.

induction therapy      Treatment designed to be used as a first step toward shrinking the cancer and in evaluating response to drugs and other agents. Induction therapy is followed by additional therapy to attempt to eliminate whatever cancer remains.

infiltrating cancer      Cancer that has spread beyond the layer of tissue in which it developed and is growing into surrounding, healthy tissues. Also called invasive cancer.

infiltrating ductal carcinoma      The most common type of invasive breast cancer. It starts in the cells that line the milk ducts in the breast, grows outside the ducts, and often spreads to the lymph nodes.

inflammation  (in-fla-MAY-shun)    Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.

informed consent      A process in which a person learns key facts about a clinical trial, including potential risks and benefits, before deciding whether or not to participate in a study. Informed consent continues throughout the trial.

infusion      A method of putting fluids, including drugs, into the bloodstream. Also called intravenous infusion.

inoperable      Describes a condition that cannot be treated by surgery.

Institutional Review Board      IRB. A group of scientists, doctors, clergy, and consumers at each health care facility that participates in a clinical trial. IRBs are designed to protect study participants. They review and must approve the action plan for every clinical trial. They check to see that the trial is well designed, does not involve undue risks, and includes safeguards for patients.

intensity-modulated radiation therapy      IMRT. A type of 3-dimensional radiation therapy that uses computer-generated images to show the size and shape of the tumor. Thin beams of radiation of different intensities are aimed at the tumor from many angles. This type of radiation therapy reduces the damage to healthy tissue near the tumor.

interferon  (in-ter-FEER-on)    A biological response modifier (a substance that can improve the body's natural response to infections and other diseases). Interferons interfere with the division of cancer cells and can slow tumor growth. There are several types of interferons, including interferon-alpha, -beta, and -gamma. The body normally produces these substances. They are also made in the laboratory to treat cancer and other diseases.

interleukin  (in-ter-LOO-kin)    A biological response modifier (substance that can improve the body's natural response to infection and disease) that helps the immune system fight infection and cancer. These substances are normally produced by the body. They are also made in the laboratory for use in treating cancer and other diseases.

interstitial radiation therapy      A procedure in which radioactive material sealed in needles, seeds, wires, or catheters is placed directly into or near a tumor. Also called brachytherapy, internal radiation, or implant radiation.

intrahepatic  (in-tra-hep-AT-ik)    Within the liver.

intraoperative radiation therapy      IORT. Radiation treatment aimed directly at a tumor during surgery.

intraperitoneal chemotherapy  (IN-tra-per-ih-toe-NEE-al KEE-mo-THER-a-pee)    Treatment in which anticancer drugs are put directly into the abdominal cavity through a thin tube.

intrathecal  (in-tra-THEE-kal)    Describes the fluid-filled space between the thin layers of tissue that cover the brain and spinal cord. Drugs can be injected into the fluid or a sample of the fluid can be removed for testing. 

intrathecal chemotherapy  (in-tra-THEE-kal KEE-mo-THER-a-pee)    Anticancer drugs that are injected into the fluid-filled space between the thin layers of tissue that cover the brain and spinal cord. 

intravenous  (in-tra-VEE-nus)    IV. Within a blood vessel.

intravenous pyelogram  (in-tra-VEE-nus PYE-el-o-gram)    IVP. A series of x-rays of the kidneys, ureters, and bladder. The x-rays are taken after a dye is injected into a blood vessel. The dye is concentrated in the urine, which outlines the kidneys, ureters, and bladder on the x-rays.

investigational      In clinical trials, refers to a drug (including a new drug, dose, combination, or route of administration) or procedure that has undergone basic laboratory testing and received approval from the US Food and Drug Administration (FDA) to be tested in human subjects. A drug or procedure may be approved by the FDA for use in one disease or condition, but be considered investigational in other diseases or conditions. Also called experimental.

IORT      Intraoperative radiation therapy. Radiation treatment aimed directly at a tumor during surgery.

IP      Intraperitoneal. Within the peritoneal cavity (the area that contains the abdominal organs).

IRB      Institutional Review Board. A group of scientists, doctors, clergy, and consumers at each health care facility that participates in a clinical trial. IRBs are designed to protect study participants. They review and must approve the action plan for every clinical trial. They check to see that the trial is well designed, does not involve undue risks, and includes safeguards for patients.

irradiation  (ih-RAY-dee-AY-shun)    The use of high-energy radiation from x-rays, gamma rays, neutrons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy) or from materials called radioisotopes. Radioisotopes produce radiation and can be placed in or near the tumor or in the area near cancer cells. This type of radiation treatment is called internal radiation therapy, implant radiation, interstitial radiation, or brachytherapy. Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that circulates throughout the body. Irradiation is also called radiation therapy, radiotherapy, and x-ray therapy.

irreversible toxicity      Side effects that are caused by toxic substances or something harmful to the body and do not go away.

IV      Intravenous (in-tra-VEE-nus). Injected into a blood vessel.

Jewett staging system      A staging system for prostate cancer that uses ABCD. “A” and “B” refer to cancer that is confined to the prostate. “C” refers to cancer that has grown out of the prostate but has not spread to lymph nodes or other places in the body. “D” refers to cancer that has spread to lymph nodes or to other places in the body. Also called the ABCD rating or the Whitmore-Jewett staging system.

Karnofsky Performance Status      KPS. A standard way of measuring the ability of cancer patients to perform ordinary tasks. The Karnofsky Performance scores range from 0 to 100. A higher score means the patient is better able to carry out daily activities. KPS may be used to determine a patient's prognosis, to measure changes in a patient’s ability to function, or to decide if a patient could be included in a clinical trial.

KPS      Karnofsky Performance Status. A standard way of measuring the ability of cancer patients to perform ordinary tasks. The Karnofsky Performance scores range from 0 to 100. A higher score means the patient is better able to carry out daily activities. KPS may be used to determine a patient's prognosis, to measure changes in a patient’s ability to function, or to decide if a patient could be included in a clinical trial.

laparoscopy  (lap-a-RAHS-ko-pee)    The insertion of a thin, lighted tube (called a laparoscope) through the abdominal wall to inspect the inside of the abdomen and remove tissue samples.

laparotomy  (lap-a-RAH-toe-mee)    A surgical incision made in the wall of the abdomen.

large cell carcinoma  (kar-sin-O-ma)    Lung cancer in which the cells are large and look abnormal when viewed under a microscope.

lentinan      A beta-glucan (a type of polysaccharide) from the mushroom Lentinus edodes (shiitake mushroom). It has been studied in Japan as a treatment for cancer.

leptomeningeal      Having to do with the two innermost layers of tissues that cover the brain and spinal cord.

leptomeningeal cancer      A tumor that involves the tissues that cover the brain and spinal cord.

leptomeningeal metastases      Cancer that has spread from the original (primary) tumor to the tissues that cover the brain and spinal cord.

lesion  (LEE-zhun)    An area of abnormal tissue. A lesion may be benign (noncancercous) or malignant (cancerous).

leucopenia    See leucopenia.  

leukapheresis      Removal of the blood to collect specific blood cells; the remaining blood is returned to the body.

leukemia  (loo-KEE-mee-a)    Cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of blood cells to be produced and enter the bloodstream. 

leukocyte  (LOO-ko-site)    A white blood cell. Refers to a blood cell that does not contain hemoglobin. White blood cells include lymphocytes, neutrophils, eosinophils, macrophages, and mast cells. These cells are made by bone marrow and help the body fight infection and other diseases.

leukopenia  (LOO-ko-PEE-nya)    A condition in which the number of leukocytes (white blood cells) in the blood is reduced.

lignan      A member of a group of substances found in plants that have shown estrogenic and anticancer effects. Lignans have been used in some cultures to treat certain medical problems.

limited-stage small cell lung cancer      Cancer is found in one lung, the tissues between the lungs, and nearby lymph nodes only.

linac      A machine that creates high-energy radiation to treat cancer, using electricity to form a stream of fast-moving subatomic particles. Also called mega-voltage (MeV) linear accelerator or a linear accelerator.

linear accelerator      A machine that creates high-energy radiation to treat cancer, using electricity to form a stream of fast-moving subatomic particles. Also called mega-voltage (MeV) linear accelerator or a linac.

linseed      The seed of the flax plant. It is a rich source of omega-3 fatty acid, fiber, and a compound called lignin. It is being studied in the prevention of prostate cancer. Also called flaxseed. 

liver metastases      Cancer that has spread from the original (primary) tumor to the liver.

local cancer      An invasive malignant cancer confined entirely to the organ where the cancer began.

local therapy      Treatment that affects cells in the tumor and the area close to it.

localized      Restricted to the site of origin, without evidence of spread.

locally advanced cancer      Cancer that has spread only to nearby tissues or lymph nodes.

low grade      When referring to cancerous and precancerous growths, a term used to describe cells that look nearly normal under a microscope. These cells are less likely to grow and spread quickly than cells in high-grade cancerous or precancerous growths.

lower GI series      X-rays of the colon and rectum (lower gastrointestinal tract) that are taken after a person is given a barium enema.

lumbar puncture      A procedure in which a needle is put into the lower part of the spinal column to collect cerebrospinal fluid or to give anticancer drugs intrathecally. Also called a spinal tap. 

lymph  (limf)    The clear fluid that travels through the lymphatic system and carries cells that help fight infections and other diseases. Also called lymphatic fluid. 

lymph gland      A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph glands filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. Also called a lymph node. 

lymph node  (limf node)    A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph nodes filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. Also called a lymph gland.

lymphocyte  (LIM-fo-site)    A type of white blood cell. Lymphocytes have a number of roles in the immune system, including the production of antibodies and other substances that fight infection and diseases. 

lymphocytic leukemia      A type of cancer in which the bone marrow makes too many lymphocytes (white blood cells).

lymphoma  (lim-FO-ma)    Cancer that begins in cells of the immune system. There are two basic categories of lymphomas. One kind is Hodgkin's lymphoma, which is marked by the presence of a type of cell called the Reed-Sternberg cell. The other category is non-Hodgkin's lymphomas, which includes a large, diverse group of cancers of immune system cells. Non-Hodgkin's lymphomas can be further divided into cancers that have an indolent (slowly progressing) course and those that have an aggressive (rapidly progressing) course. These subtypes behave and respond to treatment differently. Both Hodgkin's and non-Hodgkin's lymphomas can occur in children and adults, and prognosis and treatment depend on the stage and the type of cancer. 

lytic      Having to do with lysis. In biology, lysis refers to the disintegration of a cell by disruption of its plasma membrane. Lysis can be caused by chemical or physical means (e.g., high-energy sound waves) or by a virus infection.

magnetic resonance imaging  (mag-NET-ik REZ-o-nans IM-a-jing)    MRI. A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. MRI makes better images of organs and soft tissue than other scanning techniques, such as CT or x-ray. MRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. Also called nuclear magnetic resonance imaging. 

maintenance therapy      Treatment that is given to help a primary (original) treatment keep working. Maintenance therapy is often given to help keep cancer in remission.

malignant  (ma-LIG-nant)    Cancerous. Malignant tumors can invade and destroy nearby tissue and spread to other parts of the body.

malignant ascites      A condition in which fluid containing cancer cells collects in the abdomen.

malignant meningioma      A rare, quickly growing tumor that occurs in the membranes that cover and protect the brain and spinal cord (meninges).

malignant mesothelioma      A rare type of cancer in which malignant cells are found in the sac lining the chest or abdomen. Exposure to airborne asbestos particles increases one's risk of developing malignant mesothelioma.

mammogram  (MAM-o-gram)    An x-ray of the breast.

mammography  (mam-OG-ra-fee)    The use of x-rays to create a picture of the breast.

margin      The edge or border of the tissue removed in cancer surgery. The margin is described as negative or clean when the pathologist finds no cancer cells at the edge of the tissue, suggesting that all of the cancer has been removed. The margin is described as positive or involved when the pathologist finds cancer cells at the edge of the tissue, suggesting that all of the cancer has not been removed.

mastectomy  (mas-TEK-toe-mee)    Surgery to remove the breast (or as much of the breast tissue as possible).

matrix metalloproteinase      A member of a group of enzymes that can break down proteins, such as collagen, that are normally found in the spaces between cells in tissues (i.e., extracellular matrix proteins). Because these enzymes need zinc or calcium atoms to work properly, they are called metalloproteinases. Matrix metalloproteinases are involved in wound healing, angiogenesis, and tumor cell metastasis.

measurable disease      A tumor that can be accurately measured in size. This information can be used to judge response to treatment.

median      A statistics term. The middle value in a set of measurements.  

median survival time      The time from either diagnosis or treatment at which half of the patients with a given disease are found to be, or expected to be, still alive. In a clinical trial, median survival time is one way to measure how effective a treatment is.

medulloblastoma  (MED-yoo-lo-blas-TOE-ma)    A malignant brain tumor that begins in the lower part of the brain and that can spread to the spine or to other parts of the body. Medulloblastomas are a type of primitive neuroectodermal tumor (PNET).

mega-voltage linear accelerator      MeV linear accelerator. A machine that creates high-energy radiation to treat cancer, using electricity to form a stream of fast-moving subatomic particles. Also called linear accelerator or a linac.

meningeal      Refers to the meninges, the tissue covering the brain and spinal cord.

meningeal metastases      Cancer that has spread from the original (primary) tumor to the tissue covering the brain, spinal cord, or both.

meninges  (meh-NIN-jeez)    The three membranes that cover and protect the brain and spinal cord.

meningioma  (meh-nin-jee-O-ma)    A type of tumor that occurs in the meninges, the membranes that cover and protect the brain and spinal cord. Meningiomas usually grow slowly.

mesothelioma      A benign (noncancerous) or malignant (cancerous) tumor affecting the lining of the chest or abdomen. Exposure to asbestos particles in the air increases the risk of developing malignant mesothelioma.

metastasis  (meh-TAS-ta-sis)    The spread of cancer from one part of the body to another. A tumor formed by cells that have spread is called a “metastatic tumor” or a “metastasis.” The metastatic tumor contains cells that are like those in the original (primary) tumor. The plural form of metastasis is metastases (meh-TAS-ta-seez).

metastasize  (meh-TAS-ta-size)    To spread from one part of the body to another. When cancer cells metastasize and form secondary tumors, the cells in the metastatic tumor are like those in the original (primary) tumor.

metastatic  (MET-uh-STAT-ik)    Having to do with metastasis, which is the spread of cancer from one part of the body to another.

metastatic cancer      Cancer that has spread from the place in which it started to other parts of the body.

micrometastases      Small numbers of cancer cells that have spread from the primary tumor to other parts of the body and are too few to be picked up in a screening or diagnostic test.

microwave thermotherapy      A type of treatment in which body tissue is exposed to high temperatures to damage and kill cancer cells or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs. Also called microwave therapy. 

milk thistle      A plant that has been used in some cultures to treat certain medical problems, including stomach, liver, and gallbladder disorders. The active extract of milk thistle seeds is called silymarin. It is being studied in the prevention of liver damage caused by some cancer treatments. Also called Silybum marianum.

Miraluma test      A type of breast imaging test that is used to detect cancer cells in the breasts of some women who have had abnormal mammograms, or who have dense breast tissue. The Miraluma test is not used for screening, or in place of a mammogram. In this test, a woman receives an injection of a small amount of a radioactive substance called technetium 99, which is taken up by cancer cells, and a gamma camera is used to take pictures of the breasts. Also called scintimammography and sestamibi breast imaging.

mistletoe      A semiparasitic plant that grows on some types of trees. Mistletoe extracts are being studied as treatments for cancer. 

mixed glioma      A brain tumor that occurs in more than one type of brain cell, including astrocytes, ependymal cells, and oligodendrocytes.

modality      A method of treatment. For example, surgery and chemotherapy are treatment modalities. 

modified radical mastectomy  (mas-TEK-toe-mee)    Surgery for breast cancer in which the breast, most or all of the lymph nodes under the arm, and the lining over the chest muscles are removed. Sometimes the surgeon also removes part of the chest wall muscles.

monoclonal antibody  (MAH-no-KLO-nul AN-tih-BAH-dee)    A laboratory-produced substance that can potentially locate and bind to cancer cells wherever they are in the body. Many monoclonal antibodies are used in cancer detection or therapy; each one recognizes a different protein on certain cancer cells. Monoclonal antibodies can be used alone, or they can be used to deliver drugs, toxins, or radioactive material directly to a tumor.

morbidity      A disease or the incidence of disease within a population. Morbidity also refers to adverse effects caused by a treatment.

Morinda citrifolia      A tropical shrub. An extract from the fruit is being studied as a treatment for cancer, and extracts from the fruit, leaves, or roots have been used in some cultures to treat other diseases. Also called noni.

MRI      Magnetic resonance imaging (mag-NET-ik REZ-o-nans IM-a-jing). A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. MRI makes better images of organs and soft tissue than other scanning techniques, such as CT or x-ray. MRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. Also called nuclear magnetic resonance imaging. 

mucositis      A complication of some cancer therapies in which the lining of the digestive system becomes inflamed. Often seen as sores in the mouth.

multicenter study      A clinical trial that is carried out at more than one medical institution.

mutate      To change the genetic material of a cell. The changes (mutations) can be harmful, beneficial, or have no effect.

mutation      Any change in the DNA of a cell. Mutations may be caused by mistakes during cell division, or they may be caused by exposure to DNA-damaging agents in the environment. Mutations can be harmful, beneficial, or have no effect. If they occur in cells that make eggs or sperm, they can be inherited; if mutations occur in other types of cells, they are not inherited. Certain mutations may lead to cancer or other diseases.

myalgia  (my-AL-juh)    Pain in a muscle or group of muscles.

myelin  (MYE-eh-lin)    The fatty substance that covers and protects nerves.

myelogram  (MY-eh-lo-gram)    An x-ray of the spinal cord after an injection of dye into the space between the lining of the spinal cord and brain.

myeloid  (MY-eh-loyd)    Having to do with or resembling the bone marrow. May also refer to certain types of hematopoietic (blood-forming) cells found in the bone marrow. Sometimes used as a synonym for myelogenous; for example, acute myeloid leukemia and acute myelogenous leukemia are the same disease.

myelosuppression      A condition in which bone marrow activity is decreased, resulting in fewer red blood cells, white blood cells, and platelets. Myelosuppression is a side effect of some cancer treatments. When myelosuppression is severe, it is called myeloablation.

natural killer cell      NK cell. A type of white blood cell that contains granules with enzymes that can kill tumor cells or microbial cells. Also called a large granular lymphocyte.

necrosis  (ne-KRO-sis)    Refers to the death of living tissues. 

needle biopsy      The removal of tissue or fluid with a needle for examination under a microscope. Also called fine-needle aspiration.

neoadjuvant therapy  (NEE-o-AD-joo-vant)    Treatment given before the primary treatment. Examples of neoadjuvant therapy include chemotherapy, radiation therapy, and hormone therapy. 

neoplasia  (NEE-o-PLAY-zha)    Abnormal and uncontrolled cell growth.

neoplasm      An abnormal mass of tissue that results from excessive cell division. Neoplasms may be benign (not cancerous), or malignant (cancerous). Also called tumor.

neoplastic meningitis      A condition in which cancer cells spread into the meninges (membranes that surround the brain and spinal cord). 

nephrectomy  (neh-FREK-tuh-mee)    Surgery to remove a kidney or part of a kidney. In a partial nephrectomy, part of one kidney or a tumor is removed, but not an entire kidney. In a simple nephrectomy, one kidney is removed. In a radical nephrectomy, an entire kidney, nearby adrenal gland and lymph nodes, and other surrounding tissue are removed. In a bilateral nephrectomy, both kidneys are removed.

nephrotoxicity    Being toxic or destructive to kidney cells.

neuroblastoma      Cancer that arises in immature nerve cells and affects mostly infants and children.

neurocognitive      Having to do with the ability to think and reason. This includes the ability to concentrate, remember things, process information, learn, speak, and understand.

neuroectodermal tumor      A tumor of the central or peripheral nervous system.

neuropathy      A problem in peripheral nerve function (any part of the nervous system except the brain and spinal cord) that causes pain, numbness, tingling, swelling, and muscle weakness in various parts of the body. Neuropathies may be caused by physical injury, infection, toxic substances, disease (e.g., cancer, diabetes, kidney failure, or malnutrition), or drugs such as anticancer drugs. Also called peripheral neuropathy.

neurotoxicity      The tendency of some treatments to cause damage to the nervous system.

neutropenia      An abnormal decrease in the number of neutrophils, a type of white blood cell.

neutrophil  (NOO-tro-fil)    A type of white blood cell.

node-negative      Cancer that has not spread to the lymph nodes.

node-positive      Cancer that has spread to the lymph nodes.

non-Hodgkin's lymphoma      A group of cancers of the lymphoid system, including B-cell lymphoma, Burkitt's lymphoma, diffuse cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, lymphoblastic lymphoma, mantle cell lymphoma, mycosis fungoides, post-transplantation lymphoproliferative disorder, small non-cleaved cell lymphoma, and T-cell lymphoma.

non-small cell lung cancer      A group of lung cancers that includes squamous cell carcinoma, adenocarcinoma, and large cell carcinoma.

noni      Morinda citrifolia. A tropical shrub. An extract from the fruit is being studied as a treatment for cancer, and extracts from the fruit, leaves, or roots have been used in some cultures to treat other diseases. 

nonrandomized clinical trial      A clinical trial in which the participants are not assigned by chance to different treatment groups. Participants may choose which group they want to be in, or they may be assigned to the groups by the researchers.

objective improvement      An improvement that can be measured by the health care provider (for example, a decrease in pain can be measured by how much pain medicine the patient is taking).

objective response      A measurable response.

occult stage non-small cell lung cancer      Cancer cells are found in sputum (mucus coughed up from the lungs), but no tumor can be found in the lung by imaging or bronchoscopy, or the primary tumor is too small to be assessed.

off-label      Describes the use of a prescription drug to treat a disease or condition for which the drug has not been approved by the US Food and Drug Administration.

oligoastrocytoma      A rare type of brain tumor made up of two kinds of cells, oligodendrocytes and astrocytes, which are brain cells that nourish and support nerve cells. Also called mixed glioma. 

oligodendroglial tumor      A rare, slow-growing tumor that begins in the oligodendrocytes (brain cells that nourish and support nerve cells). Also called an oligodendroglioma.

oligodendroglioma  (OL-ih-go-den-dro-glee-O-ma)    A rare, slow-growing tumor that begins in the oligodendrocytes (brain cells that nourish and support nerve cells). Also called an oligodendroglial tumor.

omega-3 fatty acid      A type of fat obtained in the diet and involved in immunity.

Ommaya reservoir  (o-MY-a REZ-er-vwahr)    A device surgically placed under the scalp and used to deliver anticancer drugs to the fluid surrounding the brain and spinal cord.

oncologist  (on-KOL-o-jist)    A doctor who specializes in treating cancer. Some oncologists specialize in a particular type of cancer treatment. For example, a radiation oncologist specializes in treating cancer with radiation.

oncology      The study of cancer.

oncolysis      The breakdown, or lysis, of a tumor. This can occur by mechanical means, chemicals, or infectious agents such as viruses. Oncolytic viruses do not lyse most normal cells.

open label study      A type of study in which both the health providers and the patients are aware of the drug or treatment being given.

operable      Describes a condition that can be treated by surgery.

opportunistic infection      An infection caused by an organism that does not normally cause disease. Opportunistic infections occur in people with weakened immune systems.

osteosarcoma  (AHS-tee-o-sar-KO-ma)    A cancer of the bone that usually affects the large bones of the arm or leg. It occurs most commonly in young people and affects more males than females. Also called osteogenic sarcoma.

ototoxicity    Being poisonous to or exerting a deleterious effect upon the eighth nerve or upon the organs of hearing and balance.

outpatient      A patient who visits a health care facility for diagnosis or treatment without spending the night. Sometimes called a day patient.

overall survival      The percentage of subjects in a study who have survived for a defined period of time. Usually reported as time since diagnosis or treatment. Also called the survival rate. 

p-value      A statistics term. A measure of probability that a difference between groups during an experiment happened by chance. For example, a p-value of .01 (p = .01) means there is a 1 in 100 chance the result occurred by chance. The lower the p-value, the more likely it is that the difference between groups was caused by treatment.

p53 gene      A tumor suppressor gene that normally inhibits the growth of tumors. This gene is altered in many types of cancer.

palliative care  (PAL-ee-yuh-tiv)    Care given to improve the quality of life of patients who have a serious or life-threatening disease. The goal of palliative care is to prevent or treat as early as possible the symptoms of the disease, side effects caused by treatment of the disease, and psychological, social, and spiritual problems related to the disease or its treatment. Also called comfort care, supportive care, and symptom management. 

palliative therapy  (PAL-ee-yuh-tiv)    Treatment given to relieve the symptoms and reduce the suffering caused by cancer and other life-threatening diseases. Palliative cancer therapies are given together with other cancer treatments, from the time of diagnosis, through treatment, survivorship, recurrent or advanced disease, and at the end of life.

pancreatic cancer      A disease in which malignant (cancer) cells are found in the tissues of the pancreas. Also called exocrine cancer.

paresis    Slight or incomplete paralysis.

paresthesias      Abnormal touch sensations, such as burning or prickling, that occur without an outside stimulus.

partial remission      A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment. Also called partial response.

partial response      A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment.

pathologist  (pa-THOL-o-jist)    A doctor who identifies diseases by studying cells and tissues under a microscope.

pathology report      The description of cells and tissues made by a pathologist based on microscopic evidence, and sometimes used to make a diagnosis of a disease.

patient advocate      A person who helps a patient work with others who have an effect on the patient's health, including doctors, insurance companies, employers, case managers, and lawyers. A patient advocate helps resolve issues about health care, medical bills, and job discrimination related to a patient's medical condition. Cancer advocacy groups try to raise public awareness about important cancer issues, such as the need for cancer support services, education, and research. Such groups work to bring about change that will help cancer patients and their families.

pediatric  (pee-dee-AT-rik)    Having to do with children.

performance status      A measure of how well a patient is able to perform ordinary tasks and carry out daily activities.

perfusion      Bathing an organ or tissue with a fluid. In regional perfusion, a specific area of the body (usually an arm or a leg) receives high doses of anticancer drugs through a blood vessel. Such a procedure is performed to treat cancer that has not spread.

perioperative      Around the time of surgery; usually lasts from the time of going into the hospital or doctor's office for surgery until the time the patient goes home.

peripheral blood      Blood circulating throughout the body.

peripheral neuropathy      A condition of the nervous system that causes numbness, tingling, burning or weakness. It usually begins in the hands or feet, and can be caused by certain anticancer drugs.

PET scan      Positron emission tomography scan. A procedure in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the glucose is used. Because cancer cells often use more glucose than normal cells, the pictures can be used to find cancer cells in the body.

phase I trial      The first step in testing a new treatment in humans. These studies test the best way to give a new treatment (for example, by mouth, intravenous infusion, or injection) and the best dose. The dose is usually increased a little at a time in order to find the highest dose that does not cause harmful side effects. Because little is known about the possible risks and benefits of the treatments being tested, phase I trials usually include only a small number of patients who have not been helped by other treatments.

phase I/II trial      A trial to study the safety, dosage levels, and response to a new treatment.

phase II trial      A study to test whether a new treatment has an anticancer effect (for example, whether it shrinks a tumor or improves blood test results) and whether it works against a certain type of cancer.

phase II/III trial      A trial to study response to a new treatment and the effectiveness of the treatment compared with the standard treatment regimen.

phase III trial      A study to compare the results of people taking a new treatment with the results of people taking the standard treatment (for example, which group has better survival rates or fewer side effects). In most cases, studies move into phase III only after a treatment seems to work in phases I and II. Phase III trials may include hundreds of people.

phase IV trial      After a treatment has been approved and is being marketed, it is studied in a phase IV trial to evaluate side effects that were not apparent in the phase III trial. Thousands of people are involved in a phase IV trial.

phenylacetate      A drug being studied in the treatment of cancer.

phenylbutyrate      An anticancer drug that belongs to the family of drugs called differentiating agents.

pheresis  (fer-E-sis)    A procedure in which blood is collected, part of the blood such as platelets or white blood cells is taken out, and the rest of the blood is returned to the donor. Also called apheresis.

Philadelphia chromosome      An abnormality of chromosome 22 in which part of chromosome 9 is transferred to it. Bone marrow cells that contain the Philadelphia chromosome are often found in chronic myelogenous leukemia.

phlebitis    Inflammation of a vein.

phlebotomy      The puncture of a vein with a needle for the purpose of drawing blood. Also called venipuncture. 

photodynamic therapy  (foe-toe-dye-NAM-ik)    Treatment with drugs that become active when exposed to light. These drugs kill cancer cells.

photopheresis      A procedure in which blood is treated outside the body, with ultraviolet light and drugs that become active when exposed to light, and then returned to the body. It is being studied as a treatment for some blood and bone marrow diseases and graft-versus-host disease (GVHD). Also called extracorporeal photophoresis. 

pilocytic  (PI-lo-SIT-ik)    Made up of cells that look like fibers when viewed under a microscope.

pilot study      The initial study examining a new method or treatment.

pineoblastoma  (PIN-ee-o-blas-TOE-ma)    A fast growing type of brain tumor that occurs in or around the pineal gland, a tiny organ near the center of the brain.

placebo-controlled      Refers to a clinical study in which the control patients receive a placebo.

plasma  (PLAS-ma)    The clear, yellowish, fluid part of the blood that carries the blood cells. The proteins that form blood clots are in plasma.

platelet  (PLAYT-let)    A type of blood cell that helps prevent bleeding by causing blood clots to form. Also called a thrombocyte.

PNET      Primitive neuroectodermal tumor. One of a group of cancers that develop from the same type of early cells, and share certain biochemical and genetic features. Some PNETs develop in the brain and central nervous system (CNS-PNET), and others develop in sites outside of the brain such as the limbs, pelvis, and chest wall (peripheral PNET).