Technician on computer saving scans during a mammogram breast screening

Understanding Breast Density and Screening

Many people have dense breast tissue. It is common and not a diagnosis. Breasts are made up of fatty, fibrous and glandular tissue. Having dense breasts simply means your breasts have more glandular and fibrous tissue than fat. Understanding your breast density can help you have informed conversations with your provider about screening options and which imaging tests may be best for you.

What does it mean to have dense breasts?

Dense breasts contain more connective and glandular tissue and less fat. On a mammogram, dense tissue appears white. This can make it harder to see abnormalities because abnormalities appear white, as well. Knowing your breast density helps your provider determine if additional imaging, like an ultrasound, might be helpful to get a complete picture of your breast tissue.
Group of women smiling and hugging
According to the American Cancer Society, about 40% of women in the U.S. have dense breast tissue. For these women, mammograms alone may not be enough to find breast cancer.

How Breast Density is Measured

Breast density is determined by a radiologist when they review your mammogram images. You cannot feel dense breast tissue, and it can change over time. The state of Illinois requires providers to let their patients know if they have dense breasts.

Your provider may recommend additional imaging, like a comprehensive imaging mammogram, depending on your age, risk factors and breast density. 

The ABCD Levels of Breast Density

Scans showing four levels of breast densityBreast density is categorized into four levels:

  • A – Almost entirely fatty: Your breasts are mostly fat; mammograms can usually detect most changes easily.
  • B – Scattered fibroglandular densities: Small areas of dense tissue; mammograms are often effective enough alone.
  • C – Heterogeneously dense: Considered moderately dense; mammograms may miss some abnormalities.
  • D – Extremely dense: Considered dense; mammograms may not show all areas clearly.

No matter your category, dense breast tissue is common, and having it does not mean you have cancer. It simply means you should schedule different screenings.

Why Breast Density Matters for Screening

Dense breast tissue can make it harder for mammograms to find abnormalities. Both dense tissue and some masses or abnormalities appear white on the mammogram. This does not mean something is wrong. It means your provider may recommend additional imaging like a breast ultrasound, including Automated Breast Ultrasound (ABUS), to help see areas that mammograms may miss.

Additional imaging is optional and personalized. Not everyone with dense breasts will need extra tests, but understanding your density helps you and your provider make informed decisions about your screening plan.

Woman pressing on her own breast for density

Is having dense breasts common?

Yes. About four in 10 women in the U.S. have dense breast tissue. Having dense breasts is normal, and it does not mean you are at higher risk of breast cancer on its own. Knowing your density is about getting the right screening and peace of mind.
Woman laying down during an ABUS scan

Imaging Options for People with Dense Breasts

Mammograms are still the standard of breast cancer screening. For women with dense breasts, ultrasounds can provide additional clarity, making it easier to detect abnormalities that mammograms may miss. ABUS is an FDA-approved, automated ultrasound that creates 3D images and is especially helpful for dense tissue.

Ultrasounds are good for getting targeted images of a specific spot. ABUS is good for gathering an automatic picture of the entire breast.

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Have questions about breast density and screening?

Your provider can help you understand your breast density, discuss whether additional imaging is right for you and create a personalized screening plan.
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