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STAR is a study of 22,000 postmenopausal women at increased risk of breast cancer to determine whether raloxifene is as effective in reducing the chance of developing breast cancer as tamoxifen (Nolvadex®) has proven to be. STAR is being conducted by the National Surgical Adjuvant Breast and Bowel Project (NSABP), a network of researchers, and is supported by the National Cancer Institute (NCI). Recruitment to the study began May 25 at more than 400 centers across the United States, Puerto Rico, and Canada, and the first participants will be randomized by July to receive either tamoxifen or raloxifene. STAR is limited to postmenopausal women because raloxifene has not been adequately safety tested in premenopausal women, although such a study is under way.
The MORE data clearly show the potential of raloxifene for decreasing women's chances of getting breast cancer. As is standard in cancer research, promising preventive or treatment agents are compared to the standard of care, which in this case is tamoxifen. At the American Society of Clinical Oncology's (ASCO) May 1999 annual meeting, the society stated that it is premature to recommend the use of raloxifene to lower the risk of developing breast cancer outside a clinical trial. NCI and NSABP agree with ASCO in this regard.
Preliminary data from the MORE trial were presented at three scientific meetings previously, in May 1998 and May 1999 at the ASCO annual meetings and at the December 1998 San Antonio Breast Cancer Conference. STAR researchers were aware of these preliminary data during the design of the STAR protocol. Therefore, publication of MORE data in the June 16, 1999, Journal of the American Medical Association finalizes its peer review, but does not provide any additional data that would affect the design of STAR.
Tamoxifen was shown to reduce the chance of developing breast cancer by about half in the Breast Cancer Prevention Trial, a study of over 13,000 premenopausal and postmenopausal women at high risk of breast cancer. Tamoxifen has been in clinical trials for about 30 years. It has been approved for use to treat women with breast cancer for more than 20 years. Last October, the U.S. Food and Drug Administration (FDA) approved it for use to reduce the incidence of breast cancer in women at increased risk of the disease.
In MORE, a large study of raloxifene as a prevention agent for osteoporosis, the drug was shown to reduce the chance of developing breast cancer in women taking the drug. Raloxifene has been in clinical trials for about five years and was approved in December 1997 by the FDA to prevent osteoporosis. It has not been approved by the FDA for the reduction of breast cancer risk in any population.
In MORE, 7,705 postmenopausal women at high risk for osteoporosis, but not selected for high risk of breast cancer, were randomized to take one of two doses of raloxifene (60 mg daily or 120 mg daily, 5,129 women) or a placebo (2,576 women) for three years. Women taking either dose of raloxifene had 76 percent fewer breast cancers diagnosed than those women taking the placebo.
Both tamoxifen and raloxifene have been shown to increase the chances of developing potentially life-threatening health problems. Tamoxifen increases the risk of endometrial cancer (cancer of the lining of the uterus), deep vein thrombosis (blood clots in large veins), pulmonary embolism (blood clots in the lung), and possibly stroke. Raloxifene also increases the risk of deep vein thrombosis and pulmonary embolism. Its effect on the uterus is still under study. Information about the long-term safety of raloxifene is limited compared to the data available on tamoxifen. An important part of STAR will be to compare the long-term safety of raloxifene and tamoxifen in women at increased risk of breast cancer.
For more information about STAR and a list of participating centers:
