Commentary (Kimmick/Muss): The Effect of Tamoxifen on the Endometrium

Tamoxifen (Nolvadex) is widely used in the treatment of breast cancer. It is effective in the management of both early stage and advanced disease. The recent comprehensive meta-analysis of systemic treatment in early breast cancer reported that tamoxifen reduced the annual odds of breast cancer recurrence by 25%, and the risk of death by 16%, compared with patients not treated with tamoxifen [1]. The benefits are even more pronounced in postmenopausal patients, with 29% decreases in recurrence and 20% reduction in the risk of death. The risk of contralateral primary breast cancer is also decreased by approximately 28% in women receiving adjuvant tamoxifen [2]. This has prompted its use in prevention trials; the National Surgical Adjuvant Breast and Bowel Project Prevention trial (NSABP P1) is an ongoing trial randomizing women at high risk for breast cancer to receive tamoxifen or placebo. Tamoxifen's use in otherwise healthy women has brought attention to the few potential toxicities of the drug.