Regular mammography screening may be appropriate for women in their 40s who have certain risk factors for breast cancer, according to companion articles published in the May 1 issue of the Annals of Internal Medicine.

Current guidelines from the U.S. Preventive Services Task Force recommend that women aged 50 to 74 receive mammograms every two years. But according to the newly released companion studies—one of which evaluates risk factors and one that weighs earlier screening—the benefits and harms associated with such screenings are the same for women in their 40s who have a two-fold risk of breast cancer as they are for women over 50. Having a first-degree relative, such as a parent or sibling, who had breast cancer could raise a women's risk twofold, as could having very dense breast tissue.

Most risk factors evaluated in the first study, including race, ethnicity, body mass index and tobacco use, did not increase breast cancer risk, said Dr. Heidi Nelson, a research professor at Oregon Health & Science University, Portland, and lead author of one of the articles, in an e-mailed news release. "Our results indicate that we can focus on just a few significant risk factors to simplify approaches to risk-based screening for women in their 40s," she said.

For women in their 40s who have less than a two-fold increase in risk, the potential harms of regular screening—including the risks of false positives and overtreatment—outweigh the benefits, the researchers said.