A report on Tamoxifen, Aromatase inhibitor, Breast cancer and Letrozole

Tamoxifen, sold under the brand name Nolvadex among others, is a selective estrogen receptor modulator used to prevent breast cancer in women and treat breast cancer in women and men.

Aromatase inhibitors (AIs) are a class of drugs used in the treatment of breast cancer in postmenopausal women and in men, and gynecomastia in men.

Letrozole, sold under the brand name Femara among others, is an aromatase inhibitor which is used in the treatment of hormonally-responsive breast cancer after surgery.

Tamoxifen is also used to treat hormonally-responsive breast cancer, but it does so by interfering with the estrogen receptor.

Tamoxifen (a SERM) traditionally was the drug treatment of choice, but the ATAC trial (Arimidex, Tamoxifen, Alone or in Combination) showed that in women with localized estrogen receptor-positive breast cancer, women receiving the AI anastrozole had better results than the tamoxifen group.

The medications tamoxifen or raloxifene may be used in an effort to prevent breast cancer in those who are at high risk of developing it.

Ovarian stimulation with the aromatase inhibitor letrozole has been proposed for ovulation induction in order to treat unexplained female infertility.

The aromatase inhibitor aminoglutethimide induces the metabolism of tamoxifen.

Conversely, the aromatase inhibitor letrozole does not affect the metabolism of tamoxifen.

Aromatase inhibitors (such as exemestane and anasatrozole) may be more effective than selective estrogen receptor modulators (such as tamoxifen) at reducing breast cancer risk and they are not associated with an increased risk of endometrial cancer and thromboembolism.

These ER+ cancers can be treated with drugs that either block the receptors, e.g. tamoxifen, or alternatively block the production of estrogen with an aromatase inhibitor, e.g. anastrozole or letrozole.