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. Â Eventually this connection was understood in terms of estrogen, the female hormone produced by the ovaries. Â Some types of breast cancer cells are stimulated to divide by estrogen and therefore blocking this effect constitutes a form of treatment. Â Many anti-estrogen drugs have been tried with various degrees of effectiveness. Â Tamoxifen is perhaps the best known of these medications. Â 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. Â 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. Â Indeed, prostate cancer is sometimes treated by surgical removal of the testes. Â Drugs known as anti-androgens constitute the pharmaceutical treatment of this disease.
