Overview

There are different types of tissue inside your breasts. Some breast tissue is fatty. Other breast tissue is dense. "Dense" means your breast tissue has more milk glands, milk ducts, and fibrous tissue than fatty tissue. It is common and normal to have dense breasts.

You can't tell how dense your breasts are by looking in the mirror or feeling them. Dense breasts are seen on a mammogram. The mammogram report will say whether you have dense breasts. It's written by the radiologist who reads your mammogram.

There are four levels of breast density:

• Level 1: Almost all fatty tissue
• Level 2: Some areas of dense tissue, but mostly fatty tissue
• Level 3: Mixed dense and fatty tissue, but mostly dense tissue (also called heterogeneous)
• Level 4: Extremely dense tissue

You have dense breasts only if the report says that your breasts are level 3 or level 4. Levels 1 and 2 are called "not dense" on the report.

Things that can affect your breast density include your genetics, being pregnant or breastfeeding, and using estrogen hormone therapy. Your age can also make a difference. Younger people are more likely to have dense breasts than older people.

If you have questions about your breast density or other concerns, talk with your doctor about it.

Why is it important to know about your breast density?

Having dense breasts may affect your plans for breast cancer screening. Dense breast tissue can make it harder to see cancer on a mammogram. Dense tissue looks white onscreen, just like cancer does. In addition to a mammogram, sometimes other tests may be done to help find breast cancer in dense breasts.

Having dense breasts increases your risk for breast cancer. But having dense breasts does not increase your risk of dying from breast cancer.

On its own, having dense breasts does not put you at high risk for breast cancer. Your overall risk of cancer is based on a lot of things, like your age, if you've ever had breast cancer before, and if you have a strong family history of breast cancer.

Go to www.cancer.gov/bcrisktool to get more information about your personal risk of breast cancer.

How are dense breasts screened for breast cancer?

If you have dense breasts but no other risk factors for breast cancer, a mammogram is the recommended test. This includes a digital mammogram or a 3D mammogram (also called digital breast tomosynthesis, or DBT).

If you have dense breasts and also have other risk factors for breast cancer, talk with your doctor to decide about screening.

In some cases, if further screening is needed, a breast ultrasound or MRI may be done. Your breast cancer screening center may offer an abbreviated breast MRI (sometimes called a "fast MRI").