Some women take a short break from using postmenopausal hormone therapy before getting their breasts screened for cancer with mammography. They hope to lower their risk of being called back afterward for unnecessary extra breast imaging. But taking a short break from hormones doesn’t actually work for this purpose, according to the first large-scale randomized controlled trial to address the question. The READ (Radiological Evaluation and Breast Density) trial of more than 1,700 Group Health women is in the June 2, 2009 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, PhD, MPH, an associate investigator at Group Health Center for Health Studies in Seattle. This raises the chance of having a "false-positive." 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," 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."