Breast density and breast cancer risk in postmenopausal women, from Harvard Women’s Health Watch
Having dense breasts — that is, relatively little fat in the breast and more glandular and connective tissue, as seen on a mammogram — is one of the strongest known risk factors for breast cancer. A recent study finds that higher breast density also boosts the risk of some aggressive types of breast cancer in postmenopausal women, reports the October 2011 issue of Harvard Women's Health Watch.
Using data from the Nurses' Health Study, Harvard researchers found that the link between breast density and breast cancer was stronger for cancer confined to the ducts and lobules (in situ tumors) than for invasive cancer. But it was also stronger for certain breast cancers associated with poorer outcomes, including larger tumors, high-grade tumors, and estrogen receptor–negative tumors (which are more likely to grow and spread than estrogen receptor–positive tumors).