A woman's mammography results should tell her if she has dense breasts, so that she'll know the test may miss a breast cancer diagnosis, a radiologist told a federal advisory panel on mammography. Women with dense breasts are more likely to develop breast cancer, and their cancers may be more aggressive, recent research has found. Those who've already had breast cancer are more likely to have a recurrence if they have dense breasts. But tumor cells may be impossible to distinguish from normal cells on mammograms of women with dense breasts because both show up as white areas. "With dense tissue, cancers big and small are often not visible on the mammogram," Lisa Weinstock, MD, the founder of Women's Digital Imaging in Ridgewood, NJ told the FDA's National Mammography Quality Assurance Advisory Committee at their meeting on Friday in Maryland.