Preventive tamoxifen: safe so far.

Preventive tamoxifen: Safe so far

Healthy women with a family history of breast cancer live with the knowledge that they face an increased threat of the disease. while physicians can use mammograms to detect emerging tumors, they have no way to prevent such tumors from developing.

British researchers are now exploring the effects of tamoxifen -- a synthetic, hormone-like drug already used to treat breast cancer -- in a trial of healthy women at risk of developing the disease. Animal studies, including an April 3 report in the Journal of the National Cancer Institute, suggest that tamoxifen prevents breast cancer. However, many scientists worry about the danger of giving this drug to healthy women.

But Trevor Powles and his co-workers at the Royal Marsden Hospital in Surrey report some good news regarding tamoxifen's safety. In an ongoing study of about 500 cancer-free women receiving 200 milligrams of tamoxifen or placebo each day, they have detected no serious drug-related side effects, Powles says. After monitoring the women for up to three years, the team reports that about 15 percent of those taking tamoxifen -- which binds to estrogen receptors -- have reported mild, menopause-like symptoms such as hot flushes.

Powles cautions that it's too soon to predict long-term safety. For at least anotheve years, the researchers will continue to monitor the women for toxic reactions to the ongoing treatment and for endometrial cancer, tentatively linked to tamoxifen in previous studies. Ultimately, the study should also yield data on the drug's protective potential.

U.S. researchers plan a similar trial involving about 16,000 healthy women, says Bernard Fisher of the University of Pittsburgh, who will lead the multicenter trial.