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Staging and Prognosis
The prognosis of colorectal cancer is related to the
depth of tumor, penetration into the bowel wall, and whether the cancer
has spread to lymph nodes or other organs. These variables are represented
in various staging systems (e.g. Dukes, TNM and Numerical) which are nearly
equivalent:
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Dukes Stage
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TNM Stage
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Numerical
Stage
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Pathologic Description
|
Approximate 5-Year Survival
Percentage
|
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A
|
T1 N0 M0
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I
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Cancer limited to or just beneath the mucous
membrane
|
>90%
|
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B1
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T2 N0 M0
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II
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Cancer extends into muscular coat
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85%
|
|
B2
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T3 N0 M0
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II
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Cancer extends into or through serosa
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70-80%
|
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C
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Tx N1 M0
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III
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Cancer involves regional lymph nodes
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35-65%
|
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D
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Tx Nx M1
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IV
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Distant metastases (i.e. liver, lung)
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5%
|
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For the TNM stage: T = depth of tumor presentation; N = whether cancer has
spread to lymph nodes; M = whether there is distant metastases.
Treatment
Total removal of the tumor is considered the optimal treatment.
In addition, a thorough physical exam should be performed before surgery
to determine whether there is metastasis. This physical exam usually includes:
chest x-ray, biochemical assessment of liver function, measurement of
plasma CEA level, and colonoscopy of the entire bowel.
Radiation therapy, either before or after surgery, reduces the likelihood
of pelvic recurrences but does not appear to prolong survival.
Chemotherapy in patients with advanced colorectal cancer is only of marginal
benefit. The most popular drug is 5-fluorouracil (5-FU), but its use has
only a 15-20% likelihood of reducing a tumor by about 50% for a limited
period of time.
When there is liver metastasis, some treatments infuse chemotherapy directly
into the hepatic artery. This type of treatment is toxic and does not
appear to prolong survival.
Many treatments also combine folinic acid (also called leucovorin) with
5-FU. The administration of these two drugs for six months after resection
of tumor in patients with stage C disease leads to a 40% decrease in recurrence
rates and 30% improvement in survival. But, the effects on survival for
other stages of disease appear to be marginal.
Treatment Results
Various immunological and biological treatments
(i.e. farnesyl transferase inhibition, inhibition of the epidermal growth
factor receptor and the vascular endothelial growth factor) are undergoing
evaluation in advanced disease. The Cancer Monthly database currently
has the results (survival, side effects, etc.) for 45 recent colon cancer
therapies and 50 recent rectal cancer therapies including biological therapy,
immunotherapy, chemotherapy, radiation, and surgery.
Sign Up and See the Results Right Now
Source: Robert J. Mayer, Gastrointestinal Tract Cancer,
in HARRISON'S PRINCIPLES OF INTERNAL MEDICINE, pt. 5 § 77, at
527-531 (Dennis L. Kasper, M.D. et al., eds, 16th ed 2005).
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