Fall is the perfect time to learn more about breast cancer screening and prevention. Beginning in 2024, the FDA required women’s mammogram reports to inform them whether their breast tissue is considered dense or not dense.

Breast density refers to the makeup of your breast tissue. Breasts are made up of glandular tissue, fibrous connective tissue, and fat. Density is determined by the amount of glandular and fibrous tissue compared to fatty tissue. It is not connected to breast size or how firm your breasts feel. In fact, dense breast tissue cannot be identified through a self-exam or physical touch. The only way to determine breast density is through a mammogram.

Dense breasts are very common and are not considered unusual. Nearly half of all women who undergo mammograms have dense breast tissue.

Why Breast Density Is Important

Women with dense breasts may have a greater risk of developing breast cancer compared to women with less dense breast tissue. In addition, dense tissue can make it more challenging for radiologists to detect cancer during a mammogram.

On mammogram images, both dense tissue and tumors typically appear white. Because they can look alike, small cancers may be harder to identify. Less dense fatty tissue appears darker on the image, creating greater contrast and making abnormalities easier to spot.

Despite these challenges, mammograms remain one of the most effective screening tools available. Digital 3D mammography can detect more cancers than traditional mammograms because it provides highly detailed, three-dimensional views of the breast.

Breast Density Categories

After your mammogram is reviewed, a radiologist assigns your breast density to one of four categories:

• Category A: The breasts consist mostly of fatty tissue.
• Category B: The breasts contain scattered areas of dense tissue mixed with fatty tissue.
• Category C: The breasts have more dense tissue, which may make it harder to see small lumps.
• Category D: The breasts are extremely dense, which may make cancer harder to detect on a mammogram.

Discuss Your Results with Your Doctor

Talk with your doctor about your breast density and what it may mean for your overall breast health. Depending on your personal risk factors, additional screening tests may be recommended along with routine mammograms.

Atrius Health offers digital mammograms in Dedham, Boston (Kenmore), Chelmsford, Somerville, and Weymouth. To schedule an appointment, please call 617-421-3100 or visit the MyHealth Online patient portal.