Breast tissue is composed of fibrous, glandular and fatty tissue. Dense breasts have much more fibrous and glandular tissue compared to fatty tissue. About 50% of women have dense breast tissue, if you are categorized as heterogeneously or extremely dense, you may wish to consider an additional screening test.
Knowing the density of your breast tissue is important because it is more difficult to detect cancer on a screening mammogram in women with dense breasts. This is because early cancer most often shows as white on a screening mammogram and dense breast tissue also shows as white, hiding the signals of an early cancer when it has the best chance for cure. Depending on how dense your tissue is, dense breast tissue may moderately increase your risk of breast cancer.
While mammography provides the map to follow in your breast health and remains the gold standard for breast cancer screening, studies have found that women with dense breast tissue may benefit from a supplemental form of breast screening.