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National Breast Cancer Prevention Study Trial Results
Fox Chase Cancer Center and its Partner hospitals were among more than 500 sites in the United States, Puerto Rico and Canada to offer the STAR study. 19,747 postmenopausal women at increased risk of breast cancer participate in this clinical trial.
Raloxifene is as effective as tamoxifen in reducing the risk of breast cancer in postmenopausal women at increased risk for the disease. These are the results of the 5-year Study of Tamoxifen and Raloxifene, or STAR Trial - one of the largest breast cancer prevention trials ever conducted.
STAR - First Prevention Trial of Its Kind
STAR, or the Study of Tamoxifen and Raloxifene, is a clinical trial that compared the osteoporosis drug raloxifene (Evista®) with tamoxifen (Nolvadex®). The goal was to see which drug was more effective in reducing the chance of getting breast cancer in postmenopausal women at increased risk of the disease.
STAR was the first clinical trial ever to compare a drug proven to reduce breast cancer risk with another drug having the potential to reduce this risk.
STAR is a study of the National Surgical Adjuvant Breast and Bowel Project (NSABP), a network of cancer research professionals. The study was funded primarily by the National Cancer Institute (NCI), the U.S. Government's main agency for cancer research.
STAR began enrolling participants in 1999. As of June 4, 2004, the study reached its goal of enrolling 19,000 women. The study results were announced in April 2006.
STAR Results and Their Significance
Initial results of the Study of Tamoxifen and Raloxifene, or STAR, show that the drug raloxifene works as well as tamoxifen in reducing breast cancer risk for postmenopausal women at increased risk of the disease. Raloxifene is currently used to prevent and treat osteoporosis in postmenopausal women. In STAR, both drugs reduced the risk of developing invasive breast cancer by about 50%.
Since 1998, tamoxifen has been the only drug available to reduce breast cancer risk. Tamoxifen has rare, but serious side effects.
Participants in STAR who were assigned to take raloxifene had fewer serious side effects from that drug than participants assigned to take tamoxifen, including fewer uterine cancers, blood clots and cataracts. STAR data also shows that menopausal side effects such as hot flashes were mild to moderate in severity and quality of life was the same for both drugs. Both tamoxifen and raloxifene also are known to protect bone health.
The FDA has approved the use of raloxifene to reduce breast cancer risk, postmenopausal women at increased risk of breast cancer now have a choice of risk-reducing drugs. These drugs do not replace the need for mammography. For women at both average and increased risk, regular mammograms, clinical breast exams and breast self-exams help detect breast cancer early.
Premenopausal women at increased risk of breast cancer may take tamoxifen as a preventive option. Raloxifene is not FDA-approved for use in premenopausal women.
P-4: The Next Breast Cancer Prevention Trial
P-4 is a breast cancer prevention clinical trial that will build on the results of the STAR Trial. P-4 will compare the winner of STAR-raloxifene-to a new class of drug called aromatase inhibitor (AI).
An AI is a drug that prevents the formation of estradiol, a female hormone, by interfering with an aromatase enzyme. Aromatase inhibitors are used as a type of hormone therapy for postmenopausal women who have hormone-dependent breast cancer.
Research done in women being treated for breast cancer has shown that an AI may prevent the recurrence of breast cancer better than tamoxifen. Like STAR, P-4 will be available to postmenopausal women at increased risk for breast cancer. Eligible women also should not have taken a selective estrogen receptor modulator (SERM) like tamoxifen or raloxifene, or an AI for more than 3 months.
P-4 is awaiting review by the National Cancer Institute. If approved, the study will involved 12,800 women in North America.
For more information about the STAR Trial or to learn about breast cancer prevention studies and programs at Fox Chase Cancer Center, call 1-888-FOX CHASE (1-888-369-2427).
Source material for some or all of this information was obtained from the National Cancer Institute (NCI) and/or the National Surgical Adjuvant Breast and Bowel Project (NSABP) web sites.