This site requires Javascript to function properly. Please enable Javascript. This site requires Cookies to function properly. Please enable Cookies. You are using a version of Internet Explorer that is not supported. Some features may not work correctly. Upgrade to a modern browser such as Internet Explorer 10 or Google Chrome .

Breast Density

Many states have passed laws, or are in the process of passing laws, requiring mammography centers to notify women about their level of breast density after they have had a mammogram. Breast density is determined by the radiologist interpreting the mammogram and does not necessarily correlate with the look or feel of the breasts.

A radiologist reviewing a mammogram may assign a breast density score on a 4-level scale and include it in your mammography report.

  • Mostly fatty
  • Some density (scattered)
  • Moderately dense (heterogeneous)
  • Extremely dense
Examples of Breast Density


Breasts are made up of varying amounts of fat, fibrous and glandular tissue, and women with dense breasts have more fibrous and glandular tissue and less fat. Dense breast tissue is not abnormal and up to 50% of women in the US are classified as having dense breasts.  

The presence of dense tissue may make it more difficult to detect cancer using mammography and may be associated with an increased risk of breast cancer. As both dense tissue and cancers are white on mammography, the denser the tissue, the more difficult it may be for the radiologist to interpret.    

In women with dense tissue, additional screening tests, such as breast ultrasound or breast MRI may be recommended, depending upon the level of breast density and individual risk of breast cancer. Women should speak with their doctor or healthcare provider for guidance.

Breast density is determined by the radiologist reviewing your mammogram. A 4-level scale based on the American College of Radiology BI-RADS (Breast Imaging Reporting and Data System) is used to categorize density (pictured above). Assessment of breast density may vary from year to year, based on the radiologist’s interpretation, as well as naturally occurring changes in breast tissue. Breast density is included in the radiologist’s report sent to your provider.

Women with dense breast tissue should still get an annual mammogram. Many cancers are seen on mammography, even with dense tissue, and mammograms have been proven to reduce breast cancer deaths.

An annual screening mammogram is recommended for women beginning at age 40, according to the American College of Radiology (ACR) and the Society of Breast Imaging (SBI). The American Cancer Society also recommends that women have the choice to begin mammography screening at age 40. For the complete, updated ACS guidelines, click here

If you have dense breasts, please talk to your provider. Together, you can decide if additional screening exams can benefit you. 

You should still get an annual mammogram. The American College of Radiology (ACR) and the Society of Breast Imaging (SBI) recommends all women have annual mammograms beginning at age 40. Women at a higher risk may benefit from starting at an earlier age. The American Cancer Society also recommends that women have the choice to begin mammography screening at age 40. For the complete, updated ACS guidelines, click here.  

Regardless of your breast density, if you have risk factors for breast cancer, such as a family history of breast or ovarian cancer, previous radiation to the chest, or prior breast biopsies with atypical cells, you should speak with your doctor or healthcare provider to determine if additional screening tests are needed. A breast cancer risk assessment can help determine your risk and what, if any, supplemental tests may be recommended. 

Remember, a breast finding of concern should never be ignored, despite a normal mammogram. If you notice any changes in your breast(s), you should speak to your doctor or health care provider and not wait until your next routine check-up. A thorough breast examination includes a combination of mammography, physical examination and breast self-examination.