MONDAY, March 14 , 2011 (HealthDay News) -- For certain women at increased risk of breast cancer, tamoxifen can protect against the disease for a decade after treatment ends, save lives and reduce medical costs, new research suggests.
For years, women considered at increased risk of breast cancer have taken tamoxifen as a preventive measure. But previous cost-effectiveness research has only accounted for breast cancer risk reduction while it is being taken, not after treatment ends.
This new study shows that protection persists for 10 years after treatment concludes.
"Whether a woman who meets these criteria should take tamoxifen is a personal decision that should be made with her doctor," said researcher Joyce Noah-Vanhoucke, a scientist at Archimedes Inc., an independent health-care modeling organization in San Francisco.
For the study, published online March 14 in the journal Cancer, Noah-Vanhoucke and her colleagues constructed a computer model to simulate a population of postmenopausal women under age 55 in a virtual clinical trial that compared five years of tamoxifen treatment with no treatment.
The researchers assessed the effects tamoxifen, known as a chemopreventative, would have on a woman's risk of breast cancer for 10 years after that treatment ended.
Because tamoxifen therapy interferes with estrogenic activity, it is effective against breast cancers known as estrogen receptor-positive, which need estrogen to grow. In the model, 78 percent of breast cancers were ER-positive, reflecting real life.
Women in the model had a breast cancer risk score of 1.66 percent or higher as computed by the Gail model, a commonly used risk-assessment tool. A score of 1.66 or more is termed high-risk.
For instance, Noah-Vanhoucke said, a 54-year-old childless woman who underwent menopause at age 52, started menstruating at age 15 and had two breast biopsies would be scored as high risk.
Among other factors, a woman who is childless or has her first child after age 30 is at higher risk, as are women who menstruate before age 12 or undergo late menopause (after 55), according to the American Cancer Society.
Because age alone (60 and older) can make a woman high risk, the researchers limited the study pool to women under 55, who are also at lower risk of getting side effects linked with tamoxifen, such as blood clots and a higher likelihood of endometrial cancer and cataracts.
The researchers found that tamoxifen's benefits in reducing breast cancer risk for 10 years after treatment stopped outweighed the side effects. Tamoxifen prevented 29 breast cancer cases and nine breast cancer deaths for every 1,000 women treated, the researchers found.
For women with a score of 1.66 or higher, the benefits of breast cancer prevention outweighed adverse side effects by a ratio of three-to-one.
Tamoxifen also saved $47,580 in health-care costs per 1,000 women treated.
''To be able to prevent that many breast cancers for 1,000 women, I think it's a significant number to be prevented," said researcher Dr. Peter Alperin, vice president of medicine at Archimedes. Women are more interested in lives saved than cost savings, he added.
Dr. Harold Burstein, co-chair of the Endocrine Therapy for Breast Cancer Update Committee for the American Society of Clinical Oncology, reviewed the findings but was not involved in the study.
The study "puts a dollar value on the potential saving if one were to have more widespread use of this drug," said Burstein, also an associate professor of medicine at Harvard Medical School and Dana-Farber Cancer Institute.
Until now, ''it has been very difficult'' to generate enthusiasm for tamoxifen as a preventive agent, Burstein said.
In 2005, only .08 percent of U.S. women, aged 40 to 79, without a personal history of breast cancer took tamoxifen as a preventive, according to a report published in 2010 in Cancer Epidemiology, Biomarkers & Prevention.
The new study and the cost modeling, Burstein said, "'will help health-care policy specialists weigh the role of tamoxifen versus other prevention strategies that may emerge."
To learn more about tamoxifen, visit the U.S. National Cancer Institute.