If lab tests show that your tumor depended on your natural hormones to grow, it will be called estrogen-receptor-positive or progesterone-receptor-positive. Such tumors are often sensitive to anti-estrogen therapy, called hormonal therapy.
Hormone therapy is used to prevent the growth, spread, or recurrence of breast cancer by blocking your body's natural hormones from reaching any remaining cancer cells.
Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the treatment of breast cancer and pregnancy. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.
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Hormone therapy includes using drugs that block the effects of estrogen or having a procedure that either removes the ovaries or makes them unable to produce hormones.
The estrogen-blocking drug tamoxifen is the most common and oldest of the hormonal therapy drugs. It has been shown to decrease the chance of recurrence in some early-stage cancers and to prevent the development of cancer in the opposite breast. Tamoxifen works by blocking estrogen from attaching to estrogen receptors on cancer cells. By blocking the estrogen receptors, it is believed that the growth of the cancer cells will be halted.
Tamoxifen is effective in pre and postmenopausal women.
Newer types of hormone therapy are called aromatase inhibitors. These drugs include anastrozole, letrozole, and examestane. They block the production of estrogen in the body, thus lowering the levels of the hormone in the blood. Aromatase inhibitors only work in postmenopausal women.
While on hormone therapy, continue to have yearly pelvic exams and PAP smears. Notify your doctor of any unusual bleeding or pain. The duration of treatment with tamoxifen or other anti-estrogen drugs should be discussed with your doctor.
Sometimes a treatment called ovarian ablation is used to treat breast cancer. Ovarian ablation means making the ovaries of premenopausal woman nonfunctional, either by removing them with surgery or by using radiation therapy. This therapy is used in premenopausal women.
Another therapy is ovarian suppression. In this therapy, a drug is given that dries up the hormone that causes the ovaries to produce estrogen. Once this medication is discontinued, the estrogen production of the ovaries gradually returns. This therapy is used in premenopausal women.