Tamoxifen is a selective estrogen receptor modulator used to treat breast cancer in various clinical settings. This drug is particularly effective for patients with estrogen receptor–positive tumors and is approved by the US Food and Drug Administration (FDA) for use in both females and males with breast cancer.

A drug used to treat certain types of breast cancer in postmenopausal women. It is also being studied in the treatment of other types of cancer. Anastrozole lowers the amount of estrogen made by the body. This may stop the growth of cancer cells that need estrogen to grow.

Exemestane (ex" e mes' tane) is an aromatase inhibitor that acts as an antiestrogen and is used to treat postmenopausal women with estrogen receptor positive breast cancer. Aromatase is the enzyme responsible for the conversion of testosterone to estrone (E1) and of androstenedione to estradiol (E2).