Having dense breasts (more fibroglandular tissue than fatty tissue, as visualized on a mammogram) reduces the sensitivity of mammography by masking breast cancers and carries a 1.6- to 2.0-fold increased independent risk for breast cancer. To inform women about these risks, 38 U.S. states and the federal government have enacted legislation requiring a written dense breast notification (DBN) of a patient's breast density after a mammogram, but there still is limited evidence about what breast density means, and what the implications are, to women. According to a new study, while women are receiving these notifications about their breast density, not all recipients are fully understanding what they mean in terms of future health implications. Boston University School of Medicine researchers suggest that knowledge about breast density and its associated risks is partly linked to women's race/ethnicity and health literacy.