Two drugs halve risk of breast cancer, research shows

LOS ANGELES -- Tamoxifen and raloxifene -- taken by women at high risk for breast cancer -- reduce the risk of the disease by about 50 percent in high-risk post-menopausal women while they are taking the medications, researchers said Monday.

The benefits of raloxifene fall off faster once women stop taking it, however, and the increased benefits of tamoxifen come at a price: a higher risk of uterine cancer, blood clots and cataracts -- although the absolute risks of all three remain low.

"These are relatively inexpensive drugs that reduce breast cancer by about 50 percent with side effects that are modest," said Dr. Gabriel Hortobagyi of the University of Texas M.D. Anderson Cancer Center in Houston, one of the researchers.

"We need to reassess why we are not using these drugs more broadly," he said at a news conference at a meeting of the American Association of Cancer Research, where the results were presented.

The new results represent an extension of a clinical trial that was first reported in 2007 and allow refinement of the researchers' earlier conclusions.

But the basic message is that women can confidently take either drug to sharply reduce their risk of dying from breast cancer.

The trial enrolled 19,747 post-menopausal women over age 35 who had an above-normal risk of breast cancer because they have breast cancer genes or a family history of the disease. The study was funded by the National Cancer Institute.