A report on Tamoxifen, Raloxifene, Breast cancer, Estrogen receptor and Endometrial cancer

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.

It is also used to reduce the risk of breast cancer in those at high risk.

Raloxifene is a selective estrogen receptor modulator (SERM) and therefore a mixed agonist–antagonist of the estrogen receptor (ER).

Tamoxifen is used for the treatment of both early and advanced estrogen receptor-positive (ER-positive or ER+) breast cancer in pre- and postmenopausal women.

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.

Tamoxifen increases the risk of postmenopausal bleeding, endometrial polyps, hyperplasia, and endometrial cancer; using tamoxifen with an intrauterine system releasing levonorgestrel might increase vaginal bleeding after 1 to 2 years, but reduces somewhat endometrial polyps and hyperplasia, but not necessarily endometrial cancer.

In 2006, the large STAR clinical study concluded that raloxifene is also effective in reducing the incidence of breast cancer.

In the Study of Tamoxifen and Raloxifene (STAR) trial, 60 mg/day raloxifene was 78% as effective as 20 mg/day tamoxifen in preventing non-invasive breast cancer.

The ERα is found in endometrium, breast cancer cells, ovarian stromal cells, and the hypothalamus. In males, ERα protein is found in the epithelium of the efferent ducts.

Raloxifene does not cause breast tenderness, endometrial hyperplasia, menstrual bleeding, or endometrial cancer.

Selective estrogen receptor modulators (e.g., tamoxifen, clomifene, raloxifene)

Risk factors for endometrial cancer include obesity, insulin resistance and diabetes mellitus, breast cancer, use of tamoxifen, never having had a child, late menopause, high levels of estrogen, and increasing age.

Estrogen and the ERs have also been implicated in breast cancer, ovarian cancer, colon cancer, prostate cancer, and endometrial cancer.

Raloxifene, a similar drug, did not raise the risk of endometrial cancer.

Additionally, G-protein coupled estrogen receptors have been associated with various cancers of the female reproductive system including breast cancer.

The selective estrogen receptor modulators reduce the risk of breast cancer but increase the risk of thromboembolism and endometrial cancer.

This treatment is effective in endometrial stromal sarcomas because they typically have estrogen and/or progestin receptors.