For years, it has been thought that “dense breasts”—a designation determined by radiologists based on the density of breast tissue—were a risk factor for breast cancer. As such, almost all women with dense breasts (about 45 percent of the female population) are advised to supplement annual mammograms with MRIs and ultrasounds. But a new report published in the Annals of Internal Medicine suggests that those increased precautions may not always be necessary. The study surveyed 365,426 women between the ages of 40 and 74, who had 831,000 mammograms between them. When researchers applied different models of predicting cancer—such as family history, age, race, and recent breast biopsies—they found that breast density alone was not always an indicator of cancer risk. Approximately half of the survey sample with dense breasts turned out to have a low risk of developing cancer. Of those with higher risk, only 24% would have benefitted from supplemental screenings. Or to put it more simply: the study demonstrates that it is possible for medical professionals to hone in on the number of women who require additional screening by considering a variety of risk factors.
Read the full story at Time.