March 16, 2009 -- Question: Why is estrogen used to treat advanced prostate cancer -- isn't estrogen for women?
Answer: Estrogen therapy for prostate cancer has undergone resurgence in the last decade or so. It was one of the other main treatments back in the 1950s for example besides surgical castration. After the drugs were discovered that worked at the pituitary level, most of us stopped using estrogen therapy because it has some risk. These risks are regularly blood clots and sometimes heart attacks or even strokes at higher doses.
After the trials were completed with the drugs that work at the pituitary level, we stopped using estrogen for many years and then rediscovered that it could still work in a fraction of men who have stopped responding to these pituitary drugs like Lupron or Zoladex. The estrogen probably works both directly at the prostate cancer cell to somehow inhibit growth, and these mechanisms aren't well worked out, but also at the pituitary level.
The side effects of estrogen therapy however are more severe than the pituitary drugs. Men get breast enlargement or tenderness. They can have changes in their skin and the blood clots or heart attack risks that I mentioned. Nevertheless their voice doesn't change, they don't grow long hair and become feminized in any way. So it's a very good form of treatment and when it works can be very successful in prolonging the hormone responsive phase of prostate cancer.