Breast Density

Breast Density Notification

March 23, 2016 — Indiana Gov. Mike Pence signed an amendment to the state’s 2013 breast density reporting bill Wednesday expanding the requirements for notification. The amended law goes into effect July 1, 2016.

The state had previously enacted Senate Enrolled Act (SEA) 414 three years ago, which required notification in the mammography report if a patient was determined to have dense fibroglandular breast tissue. SEA 414 also required the provision of insurance coverage for supplemental screening for women at least 40 years old determined to have high breast density.

Indiana became the 25th state to adopt a full breast density notification law.

What is Breast Density?

The best way to detect breast cancer in its early stages is to get regular mammograms—however, if your mammogram report says that you have dense breast tissue, you may be wondering what that means. Having dense breasts is very common and is not abnormal. First, let’s break down the different parts and what they do:

  • Breasts are made up of lobules, ducts, and fatty and fibrous connective tissue.
  • Lobules produce milk and are often called glandular tissue.
  • Ducts are the tiny tubes that carry milk from the lobules to the nipple.
  • Fibrous tissue and fat give breasts their size and shape and hold the other tissues in place.

Your breast tissue will be dense if you have a lot of fibrous or glandular tissue and not much fat. Some women have more dense breast tissue than others. For most women, breasts become less dense with age.

How will you know if you have dense breasts?

Breast density is really seen exclusively on mammograms. Some women think that their breasts are dense because they feel firm, but breast density isn’t based on how your breasts feel, their size, or their firmness. A radiologist will read your mammogram and determine if you have dense breast tissue. 

How is breast density categorized?

Radiologists use the Breast Imaging Reporting and Data System—or BI-RADS—to classify breast density into 4 categories. Breasts range from almost entirely fatty tissue to extremely dense tissue with very little fat and are organized into categories as follows:


  • Category A: Breasts are almost all fatty tissue.
  • Category B: There are scattered areas of dense glandular and fibrous tissue.
  • Category C: More of the breast is made of dense glandular and fibrous tissue (described as “heterogeneously dense”). This can make it hard to see small tumors in or around the dense tissue.
  • Category D: Breasts are extremely dense, which makes it hard to see tumors in the tissue.

 Indiana requires by law that any woman who has heterogeneously dense or extremely dense breast tissue must be notified.

Why is breast density important?

Women who have dense breast tissue seem to have a slightly higher risk of breast cancer compared to women with less dense breast tissue. At this point in time, it’s unclear as to why dense breast tissue is linked to a higher risk of developing breast cancer.

We do know that dense breast tissue makes it harder for radiologists to see cancer. On mammograms, dense breast tissue looks white. Breast masses or tumors also look white, so the dense tissue can potentially hide tumors. In contrast, fatty tissue looks almost black. On a black background, it’s far easier to see a tumor that looks white. 

If you have dense breast tissue, do you still need a mammogram?

Yes! Most breast cancers can be seen on a mammogram, even in women who have dense breast tissue, so it’s still important to get regular mammograms. Mammograms can help save women’s lives.

Even if you have a normal mammogram result (regardless of how dense your breasts are), you should know how your breasts normally look and feel by performing regular self-examinations. Any time there’s a change, you should always report it to a healthcare provider right away.

Should you have other screening exams if you have dense breast tissue?

At this time, experts do not agree what other tests, if any, women with dense breasts should get in addition to mammograms.

Studies have shown that breast ultrasound and Magnetic Resonance Imaging (MRI) can help find some breast cancers that can’t be seen on mammograms. However, MRI and ultrasound both show more findings that turn out not to be cancer, which can lead to additional tests and unnecessary biopsies and the costs of ultrasound and MRI may not be covered by insurance.

Talk to your healthcare provider about whether you should have additional tests.

What should you do if you have dense breast tissue?

If your mammogram report says that you have dense breast tissue, talk with your provider about what this means for you. Be sure that your doctor or nurse knows your medical history and if there’s anything else in your history that increases your risk for breast cancer.