A drug used to reduce the risk of breast cancer might also reduce the risk of heart disease in healthy women, a University of Vermont researcher has found.

Mary Cushman, a medical doctor and assistant professor of medicine and pathology at the UVM College of Medicine, and a team of UVM researchers studied 111 women who participated in a nationwide breast cancer prevention trial of tamoxifen at the university. Tamoxifen is a hormone-like medication effective in reducing the occurrence of breast cancer in women at risk for the disease.

Because heart disease is the No. 1 killer of U.S. women 500,000 die from it each year Cushman wanted to know how tamoxifen might influence a woman's risk of heart disease.

Tamoxifen prevents the natural hormone estrogen from promoting the growth of breast cancer cells. It also can act like estrogen elsewhere in the body.

Other research has shown that estrogen, taken as hormone replacement therapy, might increase a woman's likelihood of heart attack in the first year of treatment, although the risk decreases over time. Tamoxifen's ability to mimic estrogen and prevent estrogen's effects in the breast made Cushman wonder how it would affect heart disease in the women who took it to prevent breast cancer.

Cushman and other researchers have reasoned that if tamoxifen raises heart disease risk, that risk might outweigh the drug's benefits in preventing breast cancer.

Whenever you use drugs for prevention, you are talking about giving medication to healthy people, and you have to weigh and balance all the benefits and risks,'' Cushman said.

The team's work, published in the February issue of Arteriosclerosis, Thrombosis and Vascular Biology: Journal of the American Heart Association, showed that tamoxifen lowered cholesterol, as well as levels of two substances associated with an increased risk of heart disease.

Because the study evaluated risk factors, and not heart disease itself, Cushman says her work raises more questions than it answers. Another study of 13,000 women, published in January, found that tamoxifen used as a breast cancer preventive neither increased nor decreased a risk of heart disease.

Considering the potential risks and benefits of this drug, it's not likely to harm a woman in terms of heart disease,'' Cushman said. ''And it may even help.''