There are 4 classes of breast density

–     Entirely fatty

–     Scattered areas of fibroglandular density

–     Heterogeneously dense (may obscure masses)

–     Extremely dense (lowers sensitivity)

Increased breast density both increases the risk of breast cancer and decreases the sensitivity of mammography to detect small lesions; Women with scattered fibroglandular/heterogeneously dense breasts (25-75% fibroglandular tissue) have 3-5x the average risk for breast cancer, especially for women who continue to have dense breasts after menopause

(Ikeda 2010)

Breast Density