Raloxifene Reduces Incidence of Breast Cancer by 58-66% and May Reduce Risk of Endometrial Cancer in Postmenopausal Women

University of Pennsylvania Cancer Center
Last Modified: May 18, 1998

Raloxifene is a novel selective estrogen receptor modulator that has estrogenic effects on bone and lipids, but estrogen antagonist effects on the breast and uterus. A new study indicates that Raloxifene, widely used for the treatment of osteoporosis, can substantially reduce the risk of breast cancer in postmenopausal women who are at normal risk for the disease, and may also decrease the risk of endometrial cancer. These findings follow the announcement of the results of a trial of tamoxifen, which found that the drug substantially reduced the risk of developing breast cancer in women at high risk of the disease, while slightly increasing the risk of other health problems, including blood clots and endometrial cancer.

A two-year study of 7,705 postmenopausal women up to 80 years (mean age 66.5 years) being treated for osteoporosis indicates that women at normal risk of developing breast cancer reduced their risk of developing the disease by approximately 66% with daily use of Raloxifene, compared to the control group. Early results also indicate no statistically significant increase in risk of endometrial cancer, a cancer of the lining of the uterus. It should be noted that these are relatively preliminary findings, and that longer-term studies will be needed to determine the full risks and benefits of the drug.

"Another weapon may be added to our arsenal of prevention with preliminary findings that raloxifene prevents breast cancer and may prevent endometrial cancer. Coming on the heels of the recent tamoxifen study, this is very exciting news," said Derrek Raghavan, MD, PhD, of the University of Southern California Norris Comprehensive Cancer Center. "However, these drugs are not for every woman. Before advocating their widespread use, further trials must be conducted to determine if these drugs actually prevent breast cancer, or merely delay it."

[ Original Abstract ]