A new report says that three drugs have been found to cut women's chances of contracting breast cancer, but each of them has distinct potential harms of its own.
Issued by HHS' Agency for Healthcare Research and Quality, the report reveals that the three drugs are tamoxifen, raloxifene, and tibolone.
The comparative effectiveness review found that all three drugs significantly reduce invasive breast cancer in midlife and older women, but that benefits and adverse effects can vary depending on the drug and the patient.
"Taking medicine to avoid breast cancer in the first place is an attractive notion, but the decision to do so must be made by patients in consultation with their clinicians with benefit of the best evidence available. These drugs are not necessarily for everyone. This report sheds important light on their advantages and potential harms," said AHRQ Director Dr. Carolyn M. Clancy.
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 US but is commonly used in other countries to treat menopausal symptoms and osteoporosis, was also 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 like sweats and 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, and that tamoxifen increases risk for endometrial cancer, hysterectomies, and cataracts compared with the other drugs.
Tamoxifen and raloxifene increase the 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 factors like age, menopausal status, oestrogen 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.