These tests can determine which drug or drug combination will or will not work for your cancer
- Most of the following information was provided by Larry M. Weisenthal, M.D., Ph.D..
- None of the information presented about assays should be used to select a cancer treatment without consulting with your licensed medical professional. But, as discussed below, be advised that some physicians are more supportive of these assays than are others.
What are these tests?
These tests or “assays” can be performed on pieces of tumors taken directly from patients. They provide information on the likelihood that different types of chemotherapy will provide clinical benefit to the patient.
What is the advantage to using these assays?
These assays are used to identify the best forms of chemotherapy for cancer patients on an individual basis. If an assay is not performed, chemo is chosen on the basis of a “one size fits all” approach. Scientists and doctors who support the use of the assays believe that by using the test to help identify the best type of treatment, toxic and ineffectual chemotherapy can be avoided.
What kind of material is used?
The tests can be performed on all solid tumors (biopsies or larger specimens) or cancer containing fluids from blood, bone marrow, or other parts of the human body.
Is there a name for these tests?
Yes, they go by a number of names including: Human Tumor Assays (the term used by Medicare) Chemosensitivity and Resistance Assays (CSRA’s), and Human Tumor Live Cell Assays (HTLCA’s).
Is there scientific proof to support the validity of these tests?
Yes, there is scientific literature documenting the correlation between test results and treatment results. The tests have been shown to identify relatively “good” and relatively “bad” forms of chemotherapy for individual patients. Patients treated with drugs active in the assays have, on average, a 7-fold greater chance of benefiting from treatment with drugs showing good results in the assays compared with treatment with drugs showing poor results in the assays. Benefits from treatment can mean both a response (temporary decrease in size of cancer) and lengthened survival.
Are these tests widely accepted and used by most hospitals?
No. You must request these tests from your oncologist and/or directly contact a lab that performs these assays. The use of these assays has been opposed by some large insurance companies and by the American Society of Clinical Oncology, based on the fact that there have been no prospective, randomized trials to “prove” that assay-directed chemotherapy provides superior results, compared to one-size-fits-all chemotherapy. In other words, while there are studies that demonstrate that these assays can and do provide helpful information to individual patients, there have not been studies in which one group of patients was treated based on an assay and another group of patients was treated with a one size fits all approach and the results of the two randomized groups were compared to see which did better.
Why haven’t these randomized trials been performed?
Prospective, randomized, controlled clinical trials cost millions of dollars, but the most promising assay technologies are public domain, non-proprietary technologies. No company will invest that much money for something that is difficult to patent. In addition, as noted by Dr. Maurie Markman of the Cleveland Clinic, the trial to prove effectiveness in one clinical situation would become instantly irrelevant with the introduction of the first new drug which wasn’t available for testing at the time of the trial.
Is their any danger in using these tests to help choose a cancer treatment?
There is a theoretical risk only in cases where a clearly superior form of one-size-fits-all
chemotherapy has been identified in controlled clinical trials. However, there are very few situations in cancer treatment where one clearly superior form of chemotherapy has been identified. One such case might be previously-untreated testicular cancer, where the combination of cisplatin/etoposide/ bleomycin on one particular schedule has been shown to be superior to all other treatments with which it has been compared. But there are almost no other situations in cancer chemotherapy in which this is true. In virtually all situations, there are several to many different forms of chemotherapy, all of which would be expected to have similar probabilities of benefit, if chosen by random selection and given to an “average” group of patients.
How much do these tests cost and are they covered by insurance?
The cost of these tests typically ranges from $1,500 to $4,000. Coverage for these tests is officially disallowed by most BlueCross/BlueShield plans (although there are exceptions, such as California Blue Shield, which does officially provide coverage for testing). Many private insurance plans (including many managed care plans) do pay for the testing. Medicare has no national policy, leaving coverage decisions up to the various regional Medicare contractors (the California Medicare contractor does provide partial coverage).
Is there additional information a patient should know?
It must also be realized that these assays are complex procedures, fraught with the potential for error and misinterpretation. The results are only meaningful to the extent that the laboratory in question is experienced and diligent in its quality assurance practices. A patient interested in this testing should not hesitate to ask specific questions and to require specific answers of the laboratories under consideration.