U.S. Task Force Issues New Guidelines on Tamoxifen for Prevention

Women at a high risk of developing breast cancer should talk with their physicians about the benefits and risks of taking drugs like tamoxifen to reduce their risk of the disease, according to the U.S. Preventive Services Task Force. The Task Force recommends that women at a low or average risk for breast cancer not take these drugs.

The Task Force is an independent panel of experts, sponsored by the Agency for Healthcare Research and Quality. The panel reviewed three randomized controlled trials that analyzed the use of tamoxifen and one study on the use of raloxifene to reduce the risk of breast cancer. The recommendations of the Task Force were published in the Annals of Internal Medicine.

"Researchers have long known that tamoxifen can reduce the chances for a second episode of breast cancer in women who have already had breast cancer. But only recently have studies been done to see whether medications can reduce breast cancer risk in healthy women who are at high risk for the disease," said Janet Allan, PhD, R.N., and vice chair of the Task Force. "The Task Force found fair evidence that tamoxifen can significantly reduce the risk for invasive estrogen-receptor-positive breast cancer by approximately 50 percent in women at high risk for the disease. We found consistent evidence for raloxifene, but it was limited to one study that focused on use of the drug to prevent fractures."

For women who are not at high risk for developing breast cancer, the Task Force recommends against the routine use of tamoxifen or raloxifene because the potential harmful side effects may outweigh the potential benefits. Side effects can include hot flashes, an increased risk of blood clots as well as endometrial cancer and uterine cancer (see related Medical Week story).

The Task Force found that the balance of benefits and detriments of taking the drugs to prevent breast cancer is more favorable for women in their 40s who are at high risk for breast cancer and have no predisposition toward blood clots, and for women in their 50s who are at high risk for breast cancer who have no predisposition to blood clots and who do not have a uterus.

Tamoxifen is the only drug currently approved by the U.S. Food and Drug Administration to reduce the incidence of breast cancer in women at high risk for breast cancer. Raloxifene is approved by the FDA for the prevention and treatment of osteoporosis, but some physicians prescribe it "off label" to reduce the risk of breast cancer.

Other sources: Agency for Healthcare Research and Quality