Estrogen receptor antagonists bind to estrogen receptors and inhibit the action of estrogen. Estrogen controls the growth of certain types of breast cancers called estrogen receptor positive cancers. So estrogen receptor antagonists are useful in treating patients with estrogen sensitive breast cancers.
Clomiphene is used to induce ovulation (egg production) in women who do not produce ova (eggs) but wish to become pregnant (infertility). Clomiphene is in a class of medications called ovulatory stimulants. It works similarly to estrogen, a female hormone that causes eggs to develop in the ovaries and be released.
Raloxifene is used to prevent and treat osteoporosis (condition in which the bones become thin and weak and break easily) in postmenopausal (women who have experienced a change of life; end of menstrual periods) women. Raloxifene is also used to decrease the risk of developing invasive breast cancer (breast cancer that has spread outside of the milk ducts or lobules into the surrounding breast tissue) in postmenopausal women who are at high risk of developing this type of cancer or who have osteoporosis. Raloxifene cannot be used to treat invasive breast cancer or to prevent invasive breast cancer from coming back in women who have already had the condition. Raloxifene also cannot be used to decrease the risk of developing noninvasive breast cancer. Raloxifene should not be used in women who have not yet experienced menopause. Raloxifene is in a class of medications called selective estrogen receptor modulators (SERMs). Raloxifene prevents and treats osteoporosis by mimicking the effects of estrogen (a female hormone produced by the body) to increase the density (thickness) of bone. Raloxifene decreases the risk of developing invasive breast cancer by blocking the effects of estrogen on breast tissue. This may stop the development of tumors that need estrogen to grow.
Tamoxifen is used to treat breast cancer that has spread to other parts of the body in men and women. It is used to treat early breast cancer in women who have already been treated with surgery, radiation, and/or chemotherapy. It is used to reduce the risk of developing a more serious type of breast cancer in women who have had ductal carcinoma in situ (DCIS; a type of breast cancer that does not spread outside of the milk duct where it forms) and who have been treated with surgery and radiation. It is used to reduce the risk of breast cancer in women who are at high risk for the disease due to their age, personal medical history, and family medical history.
