Drugs Shows Promise in Preventing Breast Cancer

Nov. 30, 2004 — -- Almost every drug has side effects, but the osteoporosis treatment drug raloxifene, or Evista, turned out to have a promising one.

Manufactured by the Eli Lilly and Co., Evista was originally designed just to prevent brittle bones, but researchers tested it twice on 7,000 women over eight years and found their breast cancer rates decreased by 60 percent.

"If it's protecting women against osteoporosis, which is a very big health problem in the United States, and as an aside it's also lowering the risk of breast cancer, so much the better," said Dr. Clifford Hudis, chief of the Breast Cancer Medicine Service at Memorial Sloan-Kettering Cancer Center in New York.

When a woman goes through menopause, her changing hormone levels can cause a greater risk of osteoporosis, heart disease, breast cancer and many other health problems.

A drug that could reduce two health risks at once would be major news.

But women who take Evista face a difficult balancing act. While the drug did prevent breast cancer, it also doubled the number of potentially dangerous blood clots that form in the eyes, lungs or legs. Researchers have more work to do.

A similar drug, Tamoxifen, has already been shown to prevent breast cancer, but it carries health risks of its own and seems to lose its effectiveness over time.

Researchers are currently working on a study comparing the two drugs to determine which is better.

"For average-risk women, we just need better answers," said Cynthia Pearson, executive director of the National Women's Health Network, a group that cautions against doctors writing millions of new prescriptions for Evista to prevent breast cancer.

"We can't rest easy here," Pearson said. "We can't say, we've found something. Not only is it effective in everyone it needs to be effective in, it is also safe."

But amid the debate, doctors say there is promise of medicines that women can safely take to help prevent breast cancer.