Breast Density

What it means to have dense breasts

Breast density refers to the ratio of fat compared to glandular/fibrous tissue in a woman’s breasts. Breast tissue is made up of milk glands, milk ducts, connective tissue (dense breast tissue) and fatty tissue (non-dense breast tissue).

When viewed on a mammogram, women with dense breasts have denser (connective) tissue, which appears white and opaque. Because breast tumors also appear white on a mammogram, the presence of dense breast tissue can make tumors and masses difficult to spot. In contrast, non-dense (fatty) breast tissue will appear dark and transparent on a mammogram.

There are four categories of breast density:

  • Almost entirely fatty
  • Scattered areas of fibroglandular density (indicating some scattered areas of density)
  • Heterogeneously dense (indicating some areas of non-dense tissue, but most the breast tissue is dense)
  • Extremely dense (nearly all the breast tissue is dense).

Having heterogeneously dense or extremely dense breast tissue can make it difficult to spot a small mass or other abnormality. A mammogram can tell you the category of your breast density.

Breast Density Chart

What you can do

  • 3D mammography and automated whole breast ultrasound offers the most detailed images possible, which means fewer false-positive readings and callbacks for additional images. It also provides greater accuracy in locating an abnormality in the breast when compared to a conventional mammogram.
  • The American Cancer Society advises women with extremely dense breast tissue to talk with their doctors about more definitive imaging.
  • Automated Whole breast ultrasound (ABUS) uses sound waves to create 3D images of breast tissue, specifically developed and FDA-approved for women with dense breast tissue.