Front page | Health and fitness | Sports | Internet guide | E-mail the Herald
Genetic Discovery May Help Determine Treatment of Prostate | |
By DR. MARLEEN MEYERS A recent discovery about the genetics of prostate gland cells may help physicians determine which patients can avoid aggressive treatment. Cancer of the prostate - a plum-shaped organ in men that lies near the bladder - is surprisingly common. Many American men will develop a prostate tumor, usually after the age of 50. In most cases, the cancer is not life-threatening. Many men in whom it is detected live for years without treatment and suffer no ill effects. But prostate cancer can be a killer, when its cancerous cells metastasize - break away -and start to grow elsewhere in the body. Currently, the best measure of the possibility of life-endangering metastases is a test for prostate-specific antigen (PSA), which is released by prostate cancer cells. An elevated PSA level doesn't necessarily mean metastases, but it is a warning signal. The recent discovery concerns the genetics of the prostate gland cell receptor for testosterone, the male sex hormone, or androgen. Testosterone is essential for many male tissues. But it also stimulates the reproduction of cancerous prostate cells. Looking at the structure of the gene for the androgen receptor, which is made up of a chain of amino acids, scientists have found one segment of the chain that seems to predict the virulence of the cancer. This segment is made up of a repeated number of molecules of one amino acid, glutamine. Studies have found that men with a large number of glutamine repeats in the chain are less likely to experience spread of the cancer to other parts of the body. The hope is for a new test that can be used alone or with the PSA test to distinguish between men who need surgery or radiation and those who require less aggressive treatment. Meanwhile, new drugs and adaptions of old medications are improving the outlook for men being treated for prostate cancer. Drug treatment is usually reserved for men with spread of prostate cancer. Advances in drug therapy now may allow prolonged survival for patients. The newest arrivals are bicalutamide (brand name Casodex) and flutamide (Eulexin), which prevent the release of androgens by the adrenal gland. Other, more investigational treatments are available, such as monoclonal antibodies, which block the receptors that allow androgens to act on prostate cells. And a new dosage of suramin, an older drug whose use has been limited by its potential toxicity, now is in the testing stage. The advisability of periodic tests for prostate-specific antigen (PSA), whose levels may rise sharply when a prostate is cancerous, should be discussed with a physician by any man 50 or older. Annual PSA tests are recommended for men in high-risk groups, such as black Americans, but not necessarily for all older men. --- Dr. Marleen Meyers is a Clinical Assistant Professor of Medicine at New York University School of Medicine. Copyright 1996 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. | |