Suramin, a drug under study for the palliative care of men with advanced prostate cancer, should be limited to persons with disease that has already been treated and has become resistant to hormone therapy, according to new research findings from the Southwest Oncology Group. Suramin has been shown to benefit men with disease that has become resistant to hormone therapy, but proved to have too many side effects when combined with hormone therapy as an initial, first-line treatment for advanced prostate cancer.
Cancer of the prostate, a male sex gland located near the bladder and rectum, is a type of cancer that occurs commonly in older men. Treatment options depend on the stage of cancer (extent of disease at diagnosis) and may include delaying treatment until the cancer progresses, or surgery, radiation therapy, chemotherapy, biologic therapy, and/or hormone therapy. Men with prostate cancer that has spread to other parts of the body (called advanced or metastatic cancer) are often treated with hormone therapy. Because the body’s male hormones, or androgens, can sometimes help the cancer to continue growing, various treatments may be used to lower the levels of these androgens (mainly testosterone). One option is the surgical removal of the testicles (called orchiectomy). Another option is the use of drugs to lower androgen levels or block the body’s use of androgens, thereby relieving the symptoms of disease and slowing the growth of the cancer. Researchers continue to study new therapies to treat advanced prostate cancer when it no longer responds to hormone therapy, and the disease progresses (called hormone-refractory disease).
Various chemotherapy combinations, particularly with the drug estramustine, have been shown to provide pain relief and improved functioning for men with hormone-refractory prostate cancer. A drug, called suramin, has also been studied over the past decade for its potential use against prostate cancer; however, it has been associated with side effects, such as suppression of the adrenal gland. For this reason, persons receiving suramin often must also receive hydrocortisone, a substance normally produced in the body by the adrenal gland. Past reports on suramin as a treatment for prostate cancer have produced conflicting results, with 1 recent study reporting that the agent was well tolerated and indeed slowed the progression of disease and reduced pain in men with hormone-refractory advanced prostate cancer.
Because of positive findings such as these, researchers from the Southwest Oncology Group studied the use of suramin in combination with hormone therapy as an initial, first-line treatment for men with newly diagnosed advanced prostate cancer. Sixty-two such patients received suramin, hydrocortisone, and hormone therapy to reduce androgen levels with either goserelin or leuprolide. The results showed that this combination increased side effects such that subsequent administration of suramin was not possible in the majority of patients.
From these findings, it appears that treatment with suramin should be limited to persons with advanced prostate cancer who have been previously treated and have hormone-refractory disease. Individuals with hormone-refractory prostate cancer may wish to talk with their doctor about the risks and benefits of receiving suramin or of participating in a clinical trial in which other promising new treatments are being studied. Two sources of information on ongoing clinical trials that can be discussed with a doctor include a comprehensive, easy-to-use service provided by the National Cancer Institute (cancer.gov) and the Clinical Trials section and service offered by Cancer Consultants.com (www.411cancer.com). (Journal of Clinical Oncology, Vol 18, No 5, pp 1043, 2000)
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