Bone drug prevents one type of breast cancer: study

WASHINGTON (Reuters Life!) - The osteoporosis drug Evista can help prevent breast cancer -- but only the type fueled by the hormone estrogen, researchers reported on Tuesday.

So-called estrogen-receptor-positive breast cancer is the most common type and women who took Eli Lilly and Co's Evista were 55 percent less likely to develop this type of cancer than women taking a placebo, the researchers reported in the Journal of the National Cancer Institute.

Evista, known generically as raloxifene, is already approved for reducing the risk of breast cancer in women past menopause who have osteoporosis.

Because it acts on estrogen, scientists had assumed it would be more effective against estrogen-receptor-positive breast cancer but no one had demonstrated this.

Dr. Deborah Grady of the University of California, San Francisco and colleagues tested this, using a group of 10,000 women who originally volunteered for a study to see if the drug can lower the risk of heart disease.

The Raloxifene Use for the Heart (RUTH) trial showed that the drug did not protect against heart disease. But it did reduce the risk of invasive breast cancer by 44 percent over 5.6 years, compared with women not taking the drug.

Half the women got Evista and half got a placebo. Those who took raloxifene had a 55 percent reduction in the risk of developing invasive ER-positive breast cancer.

There was no reduction in the risk of other types of breast cancer, including noninvasive breast cancer, often called carcinoma in situ.

Raloxifene is a selective estrogen receptor modulator, or SERM, and prevents osteoporosis in a different way than other types of drugs known as bisphosphonates.