Breast Density

Breast density refers to the amount of fibrous and glandular tissue in the breast relative to the amount of fatty tissue. Breasts are made up of different types of tissue, including glandular tissue, which produces milk, and fatty tissue, which cushions and protects the glandular tissue.

Breast density is typically measured using a mammogram. A radiologist will examine the mammogram and assign a density category based on the appearance of the breast tissue. There are four categories of breast density:

1. Almost entirely fatty: The breasts have little dense tissue, and most of the breast tissue is made up of fat.

2. Scattered areas of fibroglandular density: The breasts have some areas of dense tissue, but most of the breast tissue is made up of fat.

3. Heterogeneously dense: The breasts have many areas of dense tissue, which can make it more difficult to detect small tumors on a mammogram.

4. Extremely dense: The breasts have a very high amount of dense tissue, which can make it more difficult to detect small tumors on a mammogram.

Having dense breasts is not abnormal, and it is estimated that about 40% of women in the United States have dense breast tissue. However, dense breast tissue has been associated with an increased risk of breast cancer, as tumors can be more difficult to detect on mammograms. Women with dense breasts may be advised to undergo additional screening tests, such as ultrasound or magnetic resonance imaging (MRI), in addition to mammography.