Mammograms Not Improved by a Break from Hormone Therapy

Some women take a short break from using postmenopausal hormone therapy before getting their breasts screened for cancer with mammography. They do this in hopes of lowering their risk of being called back afterward for unnecessary additional breast imaging. But taking a short break from hormones does not in fact work for this purpose, according to the first large-scale randomized controlled trial to address the question.

Findings from the READ (Radiological Evaluation and Breast Density) trial of more than 1,700 Group Health women was published in the June 2, 2009, issue of the journal Annals of Internal Medicine. "Postmenopausal hormones make breasts denser--like young women's breasts--and make mammograms harder to ‘read,'” explained Diana S.M. Buist, Ph.D., MPH, an associate investigator at Group Health Center for Health Studies (Seattle, WA, USA). This raises the chance of having a false-positive result. That means women are called back (recalled) for more testing, only to learn they have no breast cancer after all.

"False-positives account for a quarter of the overall costs of mammography in the United States,” Dr. Buist said. Previous evidence showed stopping hormones could improve mammography, which led some clinicians to suggest stopping briefly before a mammogram. But there was no evidence of how long women needed to stay off hormones for their mammograms to improve. "We thought it was important to see if stopping hormones for one or two months really did make any difference in clinical outcomes,” she said. "And we also wanted to make sure that it didn't cause any harm.”

It did not work in practice, according to the READ trial. The trial's three groups did not differ significantly in what proportion was called back for more tests after screening mammography. Of the women (aged 45-80) who stayed on hormone therapy, 11.3% were called back for more tests, compared to 12.3% and 9.8%, respectively, of those who stayed off hormones for one or two months. Taking a break from hormone therapy was not without harm: increasing the women's menopause symptoms. But there was also some benefit--making their breasts slightly less dense.

A breast is dense if it consists of more milk glands than fat. Dense breast tissue, such as milk glands, is denser and looks white on an X-ray, making tumors harder to see. That is why any tumors are harder to detect on mammograms of denser breasts than on those of less dense breasts. Breast density tends to decline with age, but individual women differ in the density of their breasts. Aside from age, having dense breasts is the biggest risk factor for breast cancer.

"We really hoped to find that a brief break in hormone therapy would lower false-positives and remove unnecessary costs and anxiety by improving mammography,” Dr. Buist said. "And we were disappointed to find that it didn't. But we'll keep trying to find ways to reduce recall rates for women--in hopes of making mammography more effective and ensuring women have to go through the least amount of testing and radiation that's necessary.”

The READ trial is part of Group Health's ongoing research on the comparative effectiveness of tests, treatments, and preventive actions--and figuring out which ones work and which don't in real clinical settings. "These types of studies are being called for increasingly as America and policy makers think about how to reform our healthcare system,” Dr. Buist stated. "Studies like this are important for making sure that we are basing medicine on evidence and providing the most effective health care. This study does not change our clinical message to doctors or patients about hormone therapy.”

The U.S. Department of Defense (Washington, DC, USA) funded the READ trial, which enrolled women from Group Health's Breast Cancer Screening Program. "After our trial, as before it, women should engage in shared decision-making with their doctors about whether or not to take hormones for their menopause symptoms--and if so, for how long,” added Dr. Buist's coauthor, Susan D. Reed, M.D., MPH. "Even women who find hormone therapy helps their symptoms should reassess yearly whether to continue hormone therapy,” added Dr. Reed, a professor of obstetrics and gynecology at the University of Washington (Seattle, USA) and an affiliate investigator at Group Health Center for Health Studies.

Related Links:
Group Health Center for Health Studies