The American Cancer Society Responds to Preliminary Results of Raloxifene Trials

American Cancer Society
Thursday, 23 April 1998

This week, preliminary results of two new clinical trials on the drug raloxifene, which may prevent breast cancer without increasing risk of uterine cancer, were reported in the news media. The two new studies have not yet been published in a scientific journal or presented at scientific meetings; results will be presented at the American Society of Clinical Oncology (ASCO) meeting May 16-19 in Los Angeles.

The new studies, sponsored by Eli Lilly and Company, were conducted in medical centers in the US and Europe and involved 19,000 postmenopausal women. In one of the new trials, the incidence of new breast cancers was reduced 74 percent in women who took it over an average of two years and five months. During the study, twice as many women were given raloxifene as those in a control group who received a placebo. Eleven of the women on raloxifene had new breast cancers diagnosed during the study, while 21 women in the control group were diagnosed with new breast cancers. Users had a lower rate of endometrial (uterine) cancer than those who took placebos.

The preliminary results of these studies are encouraging, but more research is needed to show whether raloxifene is effective in preventing breast cancer over the long term," says Harmon Eyre, MD, executive vice president for Research and Cancer Control for the American Caner Society. "At this time it would be premature for the Society to make a recommendation regarding the use of this drug without reviewing the results from the clinical trials."

Earlier this month, the drug tamoxifen was shown to prevent breast cancer in high-risk women; tamoxifen use, however, is associated with certain rare but serious side effects. In the tamoxifen trials, users developed uterine cancer at more than twice the rate of those taking placebos. Raloxifene and tamoxifen are examples of a class of drugs known as selective estrogen receptor modulators, or SERMS. The goal of these drugs is to achieve the positive effects of traditional estrogen therapy, such as protecting against cardiac disease and osteoporosis, while avoiding the negative effects, like increased risk of endometrial (uterine) cancer and possibly breast cancer. Raloxifene, marketed under the name Evista by Eli Lilly & Company, is currently used to treat osteoporosis and has not been approved by the US Food and Drug Administration as a breast cancer preventive.

For more information, or to contact American Cancer Society, see their website at: www.cancer.org