Category: Biological

Other Names: Nolvadex, Istubal, Valodex

Tamoxifen is an orally active selective estrogen receptor modulator (SERM) that is used in the treatment of breast cancer and is currently the world's largest selling drug for that purpose.

Tamoxifen is currently used for the treatment of both early and advanced ER+ (estrogen receptor positive) breast cancer in pre- and post-menopausal women. It is also approved by the FDA for the prevention of breast cancer in women at high risk of developing the disease. It has been further approved for the reduction of contralateral (in the opposite breast) cancer.

In 2006, the large STAR clinical study concluded that raloxifene is equally effective in reducing the incidence of breast cancer, but after an average 4-year follow-up there were 36 % fewer uterine cancers and 29% fewer blood clots than in women taking tamoxifen.

In 2005, the ATAC trial showed that after average 68 months following a 5 year adjuvant treatment, the group that received anastrozole (Arimidex) had significantly better results than the tamoxifen group. Anastrozole vs tamoxifen: deaths - 575 vs 651, recurrences - 402 vs 498, distant metastases - 324 vs 375, second breast cancer - 35 vs 59 (42% reduction). The trial suggested that anastrozole should be the preferred medication for postmenopausal women with localized breast cancer that is estrogen receptor positive.

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