The AHRQ report compared tamoxifen with another SERM, raloxifene, which is primarily used to prevent and treat osteoporosis and was approved by the FDA for breast cancer risk reduction in 2007. A third drug, tibolone, which has not been approved by the FDA for use in the United States but is commonly used in other countries to treat menopausal symptoms and osteoporosis, also was included in the study.

The report found that all three drugs reduce the occurrence of breast cancer but have various side effects. The most common side effects for tamoxifen are flushing and other vasomotor symptoms (e.g., night sweats, hot flashes), vaginal discharge and other vaginal symptoms such as itching or dryness; for raloxifene, side effects include vasomotor symptoms and leg cramps; and for tibolone, side effects include vaginal bleeding.

The report also found that each drug carried the risk of adverse effects. It found that tamoxifen increases risk for endometrial cancer, hysterectomies, and cataracts compared with the other drugs. Tamoxifen and raloxifene increase risk of blood clots, although tamoxifen's risk is greater. Tibolone carries an increased risk of stroke.

The report also examined the drugs' effectiveness and harms based on such factors as age, menopausal status, estrogen use, and family history of breast cancer and sought to identify the kinds of women who might be good candidates for prevention therapy, although the evidence is limited in this area. The report called for more research to more clearly identify characteristics of patients who would benefit from these drugs while suffering the least harm.

Source: effectivehealthcare.ahrq