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Breast Cancer Study Update Confirms Effectiveness of Two Drugs used in Prevention
It’s proven: ‘time will tell.’ After 81 months of follow up, 67 area women enrolled in one of the largest breast cancer prevention trials ever conducted now have confirmation that two drugs — Raloxifene and Tamoxifen are effective in preventing breast cancer.
An update of the results of the Study of Raloxifene and Tamoxifen (STAR P-2 trial in breast cancer prevention) shows that the drug raloxifene (initially used to prevent and treat osteoporosis in postmenopausal women) improved its effectiveness against noninvasive breast cancer, caused significantly less endometrial cancer, and was significantly less toxic than tamoxifen. Although raloxifene was slightly less effective against invasive breast cancer, it still maintained strong efficacy.
Community Hospital in Munster participated in the STAR Study, one of the largest breast cancer prevention clinical trials ever conducted. STAR enrolled 19,490 postmenopausal women who were at increased risk for the disease in the follow-up study. At Community Hospital, 67 women were enrolled — one of the largest groups in the country.
“We are very proud of our efforts to bring this important study to the women of our community,” said Don Fesko, Community Hospital CEO. “Our participation in this study and the effort of the Community Cancer Research Foundation to improve access to research is helping ensure that area patients are among the first to benefit from advances in cancer care.”
The long-term STAR trial is coordinated by the National Surgical Adjuvant Breast and Bowel Project (NSABP), a network of cancer research professionals, and is sponsored by the National Cancer Institute, part of the National Institutes of Health.
Participants were randomly assigned to receive either 60 mg of raloxifene (Evista®) (9,754 participants) or 20 mg of tamoxifen (Nolvadex®) (9,736 participants) daily. The 81-month study results (versus the 47 months in the initially published report) show that raloxifene retained 76% of the effectiveness in preventing invasive disease and grew closer to tamoxifen in preventing noninvasive disease, while remaining less toxic. The relative effects of the drugs in the longer term are more consistent with expected profiles, including greater potency of tamoxifen in preventing invasive and noninvasive disease, and, significantly, less endometrial toxicity with raloxifene.
“These results help clarify that both raloxifene and tamoxifen are good preventive choices for high risk postmenopausal women depending largely on a woman’s risk factors,” said Norman Wolmark, MD, NSABP Chairman. “The results of this longer-term study should encourage wide spread acceptance of raloxifene and greater acceptance of tamoxifen for breast cancer prevention among postmenopausal women at an elevated risk, ultimately reducing the burden of breast cancer on the public health.”
“Women from Community Hospital and those enrolled in STAR across the country are true pioneers by helping to advance our knowledge of how to prevent breast cancer,” said Oncologist Erwin Robin, M.D., Principal Investigator of the STAR trial offered through Community Hospital. “It is because of their participation we are able to build on the landmark work that has been done to prevent cancer. We’ve had advances in early detection, and improved treatments, but the prevention of cancer is most rewarding.”
Improved detection and treatment of breast cancer have not eliminated the need for better prevention of this disease, which accounted for approximately 192,000 new cancer cases and 40,000 cancer deaths in the U.S. in 2009. Although the selective estrogen-receptor modulator (SERM) tamoxifen became the first U.S. Food and Drug Administration (FDA) approved agent for reducing breast cancer risk, it did not gain wide acceptance for prevention largely because it increased endometrial cancer and thromboembolic events. Raloxifene was approved by the FDA for breast cancer risk reduction following its pronounced efficacy in preventing invasive, but not noninvasive, breast cancer in the Phase III Study of Tamoxifen and Raloxifene. Initial STAR toxicity profiles favored raloxifene (e.g. significantly reduced thromboembolic events and, non-significantly, reduced endometrial cancer) over tamoxifen. Differences in the two drugs made it imperative to conduct longer-term follow-up to clarify their relative merits in regard to a host of benefits and risks, but particularly in regard to noninvasive breast cancer.
STAR participants were postmenopausal, at least 35-years old, and had a modified breast cancer risk as determined by their age, family history of breast cancer, personal medical history, age of first menstrual period, and age at first live birth. Eligible women were randomly assigned to receive either tamoxifen or raloxifene daily for five years. Before participating in the Study, women were instructed about the potential risks and benefits of tamoxifen and raloxifene, and then were asked to sign an informed consent document.
STAR investigator will present additional data from the long-term Study at the 101st Annual Meeting of the American Association for Cancer Research (AACR) in Washington, DC, during a special plenary session in Hall D of the Walter E. Washington Convention Center at 10 AM EDT on Monday, April 19,
2010. These results will be published simultaneously in Cancer Prevention Research, a journal of the American Association for Cancer Research. A video podcast will be available in the near future.
The makers of tamoxifen, AstraZeneca Pharmaceuticals, Wilmington, Delaware, and the maker of raloxifene, Eli Lilly and Company, Indianapolis, Indiana, provided their drugs and matching placebos for the trial without charge to participants. Eli Lilly and Company, also, gave NSABP support to defray recruitment costs at the participating centers and to help local investigators conduct the study.