Two years ago, the U.S. Preventive Services Task Force, an independent advisory board to the U.S. Department of Health and Human Services, recommended a change in mammogram guidelines, suggesting that women start getting mammograms every two years starting at 50, rather than at 40. Their decision left the medical community divided, with many doctors vowing to continue screening women when they turn 40, and women unsure of exactly what to do. A new study published in the Annals of Internal Medicine, however, may lend some support to the task force’s decision. The results suggest that women who start receiving yearly mammograms at age 40 may benefit, but may also receive more unnerving false positive results, which require additional imaging and radiation exposure, a breast cancer risk factor in and of itself. The study authors collected data from nearly 170,000 women who started getting mammograms at age 40. After 10 years of annual screening, anywhere from 29 to 77 percent of women would receive at least one false positive result and 7 to 9 percent would receive recommendations to undergo a biopsy based on those false positive results. That may not sound like much, but if a woman has an annual mammogram starting at 40, she’ll have 34 screenings and, potentially, three breast-cancer scares if she lives to the average age for women. If women were to follow the task force’s recommendation, the number of screenings would drop – and so would the number of false positives. The number of advanced cancer cases diagnosed with biennial screening in women of any age was just 2 to 3 percent higher than with annual screening. Although the study was focused on inaccurate breast cancer diagnoses, women can also be put at risk by too many screenings in other ways. “The more often you have mammograms, the more radiation you’re exposed to,” says Diana Zuckerman, PhD, president of the National Research Center for Women & Families. “It’s an issue that nobody wants to talk about because they don’t want to scare women into never getting mammograms.” The Bottom Line: Determine your own comfort level. The task force and the most current study’s authors both advise that any women with predetermined risk factors for breast cancer (family history or certain genes) start getting screened at age 40. But, “for a women with lower risk, it might make sense to start later or screen every other year,” says Zuckerman. “You can get one when you’re 40, and then get one when you’re 45, if you’re not sure whether to start at 40 or 50. There’s no magic about every year versus every other year.” “You, as an individual, should decide on own risk factor, how much you worry, how important it is for you to be diagnosed early,” she adds.