STAR Study Results

Initial Results of the Study of Tamoxifen and Raloxifene (STAR) Released:  Osteoporosis Drug, Raloxifene Shown to be as Effective as Tamoxifen in Preventing Invasive Breast Cancer

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.  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 4 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, one of the largest breast cancer prevention clinical trials ever conducted, 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 will continue to provide the study drugs until all the participants have completed their five years on the drug along with an additional two years of post-drug follow-up.  The trial is coordinated by the National Surgical Breast and Bowel Project (NSABP) and is sponsored by the National Cancer Institute (NCI).

In Montana and Wyoming, 122 women on STAR are currently being followed by the Montana Cancer Consortium.