Ask the Care Team
What do the results of the recently concluded STAR trial mean for the hope of preventing breast cancer?
In April, the National Cancer Institute reported on the STAR trial, a large, five-year-long clinical study comparing an older drug, tamoxifen, with raloxifene, a relatively new drug used primarily to treat osteoporosis. Tamoxifen has long been used as a treatment for breast cancer to prevent recurrences, but has some potentially dangerous side effects that have slowed its acceptance by patients for risk reduction (prevention).
The government-sponsored research asked whether raloxifene, which has a better safety profile and is approved for use in treatment and prevention of osteoporosis, was as effective as tamoxifen in reducing the risk of developing invasive breast cancer. The drugs were compared in 19,747 postmenopausal women having an elevated risk of developing breast cancer, including 226 at New England health care facilities headed by Dana-Farber.
The results: There were nearly identical numbers of invasive breast cancers – 167 among those taking raloxifene and 163 cases in the tamoxifen group. This was about half the number of breast cancers that would have been expected to occur without medication. However, there were more noninvasive (DCIS) breast cancers in the raloxifene group. Risks of rare side effects such as uterine cancer or blood clots in deep veins or the lungs were slightly lower in the raloxifene group, but the difference wasn’t statistically significant.
Dr. Judy Garber, who led Dana-Farber’s participation in the study, said "From STAR and other studies we know that medications like tamoxifen and raloxifene are remarkably effective in reducing breast cancer risk, but, like all medications, they do have side effects. The next set of studies will explore whether other medications are even more effective and produce fewer or different side effects." These studies have already begun.
What the results mean is that women now have a choice of two drugs for prevention, and should consult their doctors about which to use.
