What is hormone therapy for breast cancer?
Hormone therapy for breast cancer is used in early and advanced breast cancer. It may also be used by women who are at high risk for breast cancer—to lower their chances of getting breast cancer. Hormone therapy for breast cancer is different from hormone replacement therapy that is used to treat the symptoms of menopause.
Some breast cancers need the hormones estrogen or progesterone to grow. These cancers are called hormone-sensitive or hormone-dependent cancers. For breast cancers that are estrogen-receptor-positive (ER+), progesterone-receptor-positive (PR+), or both (ER+/PR+), hormone therapy may be used to slow or stop cancer growth.
How does hormone therapy work?
Hormone therapy works by blocking the ovaries from making estrogen, blocking enzymes that are needed when the body makes estrogen, or by blocking estrogen's effects on cancer cell growth. It includes:
- Taking medicines called selective estrogen receptor modulators (SERMS), such as raloxifene (Evista), tamoxifen (Nolvadex), and toremifene (Fareston).
- Taking medicines called aromatase inhibitors, such as anastrozole (Arimidex), exemestane (Aromasin), and letrozole (Femara). These are used mostly in postmenopausal women.
- Taking medicines called GnRH agonists or LH-RH agonists, such as goserelin (Zoladex) or leuprolide (Lupron).
- Taking an anti-estrogen medicine called fulvestrant (Faslodex).
- Having surgery to remove the ovaries or getting radiation to the ovaries. These are permanent ways to stop the ovaries from making estrogen.
After treatment for early-stage breast cancer, hormone therapy may be used to reduce the chances of having breast cancer come back (recurrence). Usually this means taking tamoxifen or an aromatase inhibitor for 5 or more years.
Hormone therapy may be used to treat advanced or metastatic breast cancer.
Hormone therapy may also be used for women who have an increased risk for breast cancer and who are looking to reduce their risk. Medicines that may help prevent breast cancer in women who are at high risk include anastrozole, raloxifene, and tamoxifen.