According to drug company Lilly it's osteoporosis drug Evista is as effective as Tamoxifen in reducing the risk of breast cancer in high-risk women.
The company says the results of a 19,000-woman Study of Tamoxifen and Raloxifene (STAR) trial show that Evista, known generically as raloxifene, is less likely than Tamoxifen to cause blood clots and uterine cancer.
The National Cancer Institute says STAR showed that both drugs reduced the risk of developing invasive breast cancer by about 50 percent.
Tamoxifen has long been prescribed to treat and prevent breast cancer and now Lilly says it will be applying for approval from the Food and Drug Administration to market Evista in the U.S. for the treatment of osteoporosis and to prevent breast cancer.
After lung cancer, the American Cancer Society says breast cancer is the second leading cause of cancer death among U.S. women, and more than 200,000 are diagnosed and 40,000 die from it each year.
The society says the lifetime risk for a woman in the developed world is about one in nine, but having a mother or sister with the disease, never having had a child, or having had a number of suspicious-looking breast lumps, ups that risk factor.
The anxiety many women experience regarding Tamoxifen because it can raise the risk of uterine cancer and blood clots will not exist with Evista as the STAR trial has shown.
The five-year trial which involved the the National Cancer Institute, showed that a daily dose of raloxifene over a four year period gave women 36 percent fewer uterine cancers and 29 percent fewer blood clots than the women who were assigned to take Tamoxifen.
Both drugs are taken as pills and mimic the effects of the hormone estrogen on cells, although in a way that appears to be safer than estrogen itself.