The Study of Tamoxifen and Raloxifene, or STAR, is a clinical trial designed see how the drug raloxifene compares with the drug tamoxifen in reducing the incidence of breast cancer in postmenopausal women who are at increased risk of the disease. (See a summary of the protocol.) One of the largest breast cancer prevention studies ever, STAR took place at more than 500 centers across the United States, Canada, and Puerto Rico.
Initial results of STAR show that the drug raloxifene is as effective as tamoxifen in reducing the breast cancer risk of the women on the trial. In STAR, both drugs reduced the risk of developing invasive breast cancer by about 50 percent. In addition, within the study, women who were 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.
Researchers with the National Surgical Adjuvant Breast and Bowel Project (NSABP), an NCI-funded Cooperative Group, conducted the trial. STAR was funded primarily by NCI.
The links on the left of this page will take you to more detailed information about the trial and its results so far, including a variety of press materials (see STAR Background).
Breast cancer is a critical public health problem: more than 212,000 women will be diagnosed with breast cancer in the United States this year and more than 30,000 will die of the disease.