Hormone therapy is a systemic therapy used to treat breast cancer. The American Cancer Society estimates that two out of three breast cancers are estrogen-dependent, which means estrogen helps the cancer grow. Hormone therapy is used to block or reduce the amount of estrogen in the body, which helps stop or slow down cancer growth.
The American Cancer Society describes ovarian ablation as removing or shutting down the ovaries, which produce most of the estrogen in a woman’s body. Once this is done, the woman is post-menopausal. There are several ways ovarian ablation can be done. An oophorectomy is the surgical removal of the ovaries. It can be done chemically with drugs called leuteinizing hormone-releasing hormone (LHRH) analogs that prevent the body from making estrogen. Sometimes chemotherapy shuts down the ovaries, but this may not be permanent.
Aromatase inhibitors are given to post-menopausal women who have hormone-receptive breast cancer. These drugs block the enzyme aromatase from converting androgen, another hormone, to estrogen, thus lowering the amount of estrogen in the body, according to the National Cancer Institute. They are given only to women who have gone through menopause already. Because they do not stop the ovaries from making estrogen, they would not be effective in pre-menopausal women. Drugs in this category include letrozole (brand name Femara), anastrazole (Arimidex) and exemestane (Aromasin).
Tamoxifen and Toremifene (Fareston)
Tamoxifen and toremifene are anti-estrogen pills that temporarily block estrogen receptors on breast cancer cells, according to the American Cancer Society. They work by preventing estrogen from working on the cells and stopping them from reproducing. Both drugs can be given to women whose breast cancers are estrogen or progesterone receptive, and are taken as a pill daily for 5 years. Sometimes these drugs are prescribed for women who have breast cancer that has spread, metastized, to other organs. They also can be used in women at high risk for breast cancer to reduce their risk of getting the disease. A major possible side effect is the increased risk of developing uterine cancer.
Fulvestrant is a medication that destroys estrogen receptors, rather than blocking them. It is given intravenously once a month. This drug can be given only to post-menopausal women and generally is reserved for women whose cancers have stopped responding to tamoxifen or toremifene or that have spread despite treatment with these drugs, according to chemocare.com.
About this Author
After graduating with a bachelor’s degree in psychology and women’s studies, Jaime Herndon pursued an Master of Science in clinical health psychology, and recently completed her MPH in maternal-child health from UNC. Her interests include women’s cancers, pediatric oncology, and women’s health.