The first scientific observation about breast cancer was made in 1896 when it was noted that the disease sometimes regressed if the ovaries were removed. 聽Eventually this connection was understood in terms of estrogen, the female hormone produced by the ovaries. 聽Some types of breast cancer cells are stimulated to divide by estrogen and therefore blocking this effect constitutes a form of treatment. 聽Many anti-estrogen drugs have been tried with various degrees of effectiveness. 聽Tamoxifen is perhaps the best known of these medications. 聽Prostate cancer cells are also known to be stimulated by hormones, in this case by androgens, the male sex hormones which are produced mostly in the testes. 聽It has long been known that eunuchs do not develop prostate cancer because removal of the testes lowers the level of male hormones in the blood. 聽Indeed, prostate cancer is sometimes treated by surgical removal of the testes. 聽Drugs known as anti-androgens constitute the pharmaceutical treatment of this disease.
