Hormones are naturally occurring substances in the body that stimulate the growth of hormone sensitive tissues, such as the breast or prostate gland. When cancer arises in breast or prostate tissue, its growth and spread may be caused by the body's own hormones. Therefore, drugs that block hormone production or change the way hormones work, and/or removal of organs that secrete hormones, such as the ovaries or testicles, are ways of fighting cancer. Hormone therapy, similar to chemotherapy, is a systemic treatment in that it may affect cancer cells throughout the body.
Tamoxifen (Nolvadex®) is a hormone therapy used to treat breast cancer. It blocks the effects of estrogen on the cancer cells in the breast. However, tamoxifen does not stop the production of estrogen.
Arimidex® (anastrozole) and Femara® (letrozole) prevent estrogen production all together.
Another drug used for recurrent breast cancer is Faslodex®. This drug eliminates the estrogen receptor rather than blocking it, as is the case with tamoxifen, letrozole, or anastrozole. This drug is used following previous antiestrogen therapy. Side effects for fulvestrant include hot flashes, mild nausea, and fatigue.
Men who have breast cancer may also be treated with tamoxifen. Tamoxifen is currently being studied as a hormone therapy for treatment of other types of cancer.
With prostate cancer, there are a variety of hormone therapies that could be used. Male hormones, such as testosterone, stimulate prostate cancer to grow. Hormone therapy is given to help stop hormone production and to block the activity of the male hormones. Hormone therapy can cause a tumor to shrink and the prostate-specific antigen (PSA) levels to decrease.