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UnityPoint Clinic - Express (Marshalltown)

1704 South Center Street
Marshalltown, IA 50158

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Breast Density Guidelines

Effective January 1, 2018, all Iowa facilities that provide mammography service are required by law to notify patients of their breast density. This new regulation was mandated by the Iowa Department of Health.

Following a mammogram, patients will receive a letter sent directly to their homes by the UnityPoint Health – Marshalltown mammography department to inform them of their tissue density.

What is dense breast tissue?

Breasts are made up of lobules, ducts and fatty and fibrous connective tissue.

  • Lobules produce milk and are often called glandular tissue.
  • Ducts are tiny tubes that carry milk from lobules to the nipple.
  • Fibrous tissue and fat give breasts their size and shape and hold the other tissues in place.

Your breasts will be seen as dense if you have a lot of fibrous or glandular tissue and not much fat in the breasts. Some women have more dense breast tissue than others. For most women, breasts become less dense with age. But in some women, there's little change.


How do I know if I have dense breasts?

Breast density is seen only on mammograms. Some women think that because their breasts are firm, they are dense. But breast density isn't based on how your breasts feel. It's not related to breast size or firmness.

Radiologists are the doctors who "read" x-rays like mammograms. They check your mammogram for abnormal areas, and also look at breast density.

Breast density categories

Radiologists use the Breast Imaging Reporting and Data System, or BI-RADS, to classify breast density into 4 categories. They go from almost all fatty tissue to extremely dense tissue with very little fat.

Breasts are almost all fatty tissue.

There are scattered areas of dense glandular and fibrous tissue.

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.

Breasts are extremely dense, which makes it hard to see tumors in the tissue.

Some mammogram reports sent to women mention breast density. Your health care provider can also tell you if your mammogram shows that you have dense breasts.

In some states, women whose mammograms show heterogeneously dense or extremely dense breasts must be told that they have dense breasts in the summary of the mammogram report that is sent to patients (sometimes called the lay summary).

The language used is mandated by each law, and may say something like this:

"Your mammogram shows that your breast tissue is dense. Dense breast tissue is common and is not abnormal. However, dense breast tissue can make it harder to evaluate the results of your mammogram and may also be associated with an increased risk of breast cancer. This information about the results of your mammogram is given to you so you will be informed when you talk with your doctor. Together, you can decide which screening options are right for you. A report of your results was sent to your primary physician."

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. It's unclear at this time why dense breast tissue is linked to breast cancer risk.

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 hide some tumors. In contrast, fatty tissue looks almost black. On a black background it's easier to see a tumor that looks white. So, mammograms can be less accurate in women with dense breasts.

If I have dense breasts, do I still need mammograms?

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. Anytime there's a change, you should report it to a health care provider right away.

Should I have any other screening tests if I 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. But MRI and ultrasound both show more findings that turn out not to be cancer. This can lead to more tests and unnecessary biopsies. And the cost of ultrasound and MRI may not be covered by insurance.

Talk to your health care provider about whether you should have other tests.

What do I do if I'm worried about my breast density?

Together with your provider, you can determine if additional screening options are appropriate for you.

They imaging department at UnityPoint Health – Marshalltown can help you take the preventative steps needed to stay healthy. Learn more about our Mammography services today and schedule your 3D Mammogram by contacting (641) 328-7687.

Learn more about screenings and early detection related to breast cancer from the American Cancer Society.