Determining if you have dense breasts

By Nicole Ferrara • February 14, 2023

Estimated reading time: 2 minutes

By Deb Balzer

Women are encouraged to get their annual breast cancer screening because it can save lives. But what if your mammogram shows you have dense breasts?

Watch this "Mayo Clinic Minute" video to hear Christine Klassen, M.D., a Mayo Clinic Breast Clinic physician, explain what it means to have dense breasts:

For the safety of its patients, staff and visitors, Mayo Clinic has strict masking policies in place. Anyone shown without a mask was recorded prior to COVID-19 or recorded in an area not designated for patient care, where social distancing and other safety protocols were followed.

At age 40, Mayo Clinic encourages women to get their annual mammograms. You may get an unexpected result, like being told you have dense breasts.

"Breast density is a radiologic term, and it's specifically referring to how the breast tissue appears on a mammogram," says Dr. Klassen.

The breast tissue is made up of fibrous tissue, glandular tissue and fatty tissue. Dr. Klassen says dense breasts may make screening more difficult.

"The dense breast tissue on a mammogram is when we see a lot of that glandular and supportive tissue, and not so much of the fatty tissues."

Breast density is assigned one of four levels ― A, B, C, and D, which is extremely dense.

"The higher-density group has about four times the risk of cancer, compared to the lower-density group," she says.

Annual mammograms remain an important screening tool. Dr. Klassen says additional testing may help.

"We do think that there's some benefit to getting the 3D mammogram, or the mammogram with tomosynthesis, which helps radiologists scan through the field of the breast and get a better sense for what's a true mass."