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Osteoporosis drug raloxifene shown to be as effective as tamoxifen in preventing invasive breast cancer
Ann Arbor - Initial results of the Study of Tamoxifen and Raloxifene, or STAR, show that the drug raloxifene, currently used to prevent and treat osteoporosis in postmenopausal women, works as well as tamoxifen in reducing breast cancer risk for postmenopausal women at increased risk of the disease.
The University of Michigan Comprehensive Cancer Center participated in this clinical trial, one of the largest breast cancer prevention trials ever conducted. U-M researchers oversaw recruitment at three other institutions: Oakwood Healthcare System in Dearborn, Henry Ford Health System in Detroit, and Tulane University in New Orleans.
In STAR, both drugs reduced the risk of developing invasive breast cancer by about 50 percent. In addition, within the study, women who were prospectively and randomly assigned to take raloxifene daily, and who were followed for an average of about four years, had 36 percent fewer uterine cancers and 29 percent fewer blood clots than the women who were assigned to take tamoxifen. Uterine cancers, especially endometrial cancers, are a rare but serious side effect of tamoxifen. Both tamoxifen and raloxifene are known to increase a woman’s risk of blood clots.
STAR enrolled 19,747 postmenopausal women who were at increased risk of the disease. Participants were randomly assigned to receive either 60 mg of raloxifene (Evista®) or 20 mg of tamoxifen (Nolvadex®) daily for five years. The trial is coordinated by the National Surgical Adjuvant Breast and Bowel Project (NSABP), a network of cancer research professionals, and is sponsored by the National Cancer Institute (NCI), part of the National Institutes of Health.
"We still have to look at the data in depth, but it appears as if the two drugs are very, very similar. We need to look at the full statistical analyses before we can say that there is a certain subset of patients who would benefit more from one drug over the other. It is a beneficial outcome to have another drug that is likely to be approved for breast cancer prevention. At this point, however, we are advising patients not to change the drug they are taking,” says Sofia Merajver, M.D., Ph.D., professor of internal medicine at co-director of the breast cancer research program at the U-M Comprehensive Cancer Center.
"In 1998, the landmark Breast Cancer Prevention Trial showed that tamoxifen could reduce the risk of invasive breast cancer in premenopausal and postmenopausal women by nearly 50 percent," said Norman Wolmark, M.D., NSABP chairman. "Today, we can tell you that for postmenopausal women at increased risk of breast cancer, raloxifene is just as effective, without some of the serious side effects known to occur with tamoxifen."
Women taking either drug had equivalent numbers of strokes,
heart attacks, and bone fractures. Both raloxifene and tamoxifen
are known to protect bone health; it is estimated that half
a million postmenopausal women are currently taking raloxifene
by prescription to prevent or treat osteoporosis. Additionally,
the initial results from STAR suggest that
“Although no drugs are without side effects, tamoxifen
and raloxifene are vital options for women who are at increased
risk of breast cancer and want to take action,” said
Leslie Ford, M.D., associate director for clinical research
Division of Cancer Prevention. “For many
women, raloxifene’s benefits will outweigh its risks
in a way that
The STAR researchers also tracked known menopausal side effects that occur with both drugs and monitored the participants’ quality of life. The data show that side effects of both drugs were mild to moderate in severity, and quality of life was the same for both drugs.
Participants in STAR are now receiving information about which drug they were taking. Women assigned to raloxifene will continue to be provided with the drug until they have completed five years of treatment. Those women assigned to tamoxifen can choose to continue taking tamoxifen or to receive raloxifene to complete their five years of treatment.
Study details include:
Women who participated in STAR were postmenopausal, at least 35 years old, and had an increased risk of breast cancer as determined by their age, family history of breast cancer, personal medical history, age at first menstrual period, and age at first live birth. Before participating in the study, the women were instructed about the potential risks and benefits of tamoxifen and raloxifene and then were asked to sign an informed consent document.
The maker of tamoxifen, AstraZeneca Pharmaceuticals, Wilmington, Del., and the maker of raloxifene, Eli Lilly and Company, Indianapolis, Ind., provided their drugs and matching placebos for the trial without charge to participants. Eli Lilly and Company also gave NSABP support to defray recruitment costs at the participating centers and to help local investigators conduct the study.
For more information about STAR, including links to media materials and a fact sheet, visit NCI's STAR home page at or one of NSABP’s Web sites at http://www.nsabp.pitt.edu and http://foundation.nsabp.org.
A Q&A related to the STAR results.
For B-roll related to the STAR results, go to www.thenewsmarket.com for digitized, downloadable B-roll, or call the NCI Media Relations Branch at (301) 496-6641 for a Beta-tape copy.
Written by Nicole Fawcett