PROSTATE CANCER

Report #6927; 10/15/96

Doctors have known for more than fifty years that giving drugs to block the male hormone, testosterone, stops further spread of prostate cancer, but one to three years later, prostate cancer cells virtually always start to spread rapidly throughout the body. We just found out why.

Dr. Shutsung Liao, of the University of Chicago, reports in the Proceedings of the National Academy of Sciences, that prostate cancer cells have little tiny hairs on their surfaces called testosterone receptors. When testosterone binds to these receptors, it causes the prostate cancers to grow rapidly and sometimes spread through the body. So doctors treat prostate cancer that has spread to other parts of the body with drugs to block testosterone. Then, many months after testosterone is removed or blocked, prostate cancer cells markedly increase production of hair-like testosterone receptors to many times the number they had originally. At this time, the cells are loaded with testosterone receptors, and giving small amounts of testosterone can kill the cancer cells. However, before all the prostate cancer cells can be killed, some cells lose receptors/ and are stimulated to spread through the body/ by testosterone.

These experiments can lead to exciting new treatments for prostate cancer. In the future, the first stage of treatment for prostate cancer that has spread will probably be drugs to block testosterone, rather than removing the testicles. This allows the men to have readily available testosterone when they need it later. After several months when the cells become loaded with testosterone receptors, the patient will be given small amounts of testosterone with drugs to kill cancer cells, and we may have a cure.

By Gabe Mirkin, M.D., for CBS Radio News