Breast Density and Your Mammogram Report
Written July 2015
©2015, American Cancer Society, Inc. No.004802 - Rev. 7/15
Regular mammograms are the best way to find breast cancer early. But if your mammogram report said that you had dense breast tissue, you may be wondering what that means.
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 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 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. Breast density is very common, and is not abnormal.
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. There are 4 categories of breast density. They go from almost all fatty tissue to extremely dense tissue with very little fat. The radiologist decides which of the 4 categories best describes how dense your breasts are.
Some mammogram reports sent to women mention breast density. At one time, doctors assigned a number to the density category, but it’s now worded in a way that’s easier to understand. Women whose mammograms show anything more than scattered areas of dense tissue may be told that they have “dense breasts.”
Breasts are almost all fatty tissue. There are scattered areas of dense More of the breast is made of dense glandular and fibrous tissue. glandular and fibrous tissue. 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.
Why is breast density important?
Having dense breast tissue might increase your risk of getting breast cancer. Women who have dense breast tissue 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 know there are many risk factors for breast cancer – starting menstrual periods early, late menopause, first pregnancy after age 30, family members with breast cancer – just to name a few. The 2 most important risk factors are being a woman and getting older.
Women who have a strong family history of breast cancer or the breast cancer genes (BRCA1 or BRCA2) are at high risk for breast cancer. Women at high risk should have MRIs each year along with their mammograms.
Women with dense breast tissue are at moderate risk for breast cancer. MRIs are not recommended for women at moderate risk for breast cancer based on what’s known today.
Dense breast tissue makes it harder for radiologists to see cancer. On mammograms, dense breast tissue looks white, and breast masses or tumors also look white. So, the dense tissue can hide tumors. In contrast, fatty tissue looks almost black. On a black background it’s easy 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 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 with a normal mammogram report, a woman should know how her breasts normally look and feel. Anytime there’s a change, she should report it to her health care provider right away.
Are there any other tests that I should have if I have dense breast tissue?
No, at this time, experts do not agree what other tests, if any, should be done in addition to mammograms in women with dense breasts. After talking with your health care provider, you may choose to have other tests.
Studies have shown that ultrasound and magnetic resonance imaging (MRI) can help find breast cancers that can’t be seen on mammograms. But MRI and ultrasound both show more findings that are not cancer. This can lead to more tests and unnecessary biopsies. And the cost of ultrasound and MRI may not be covered by insurance.
What should I do if I have dense breast tissue?
If your mammogram report says that you have dense breast tissue, talk with your provider about what that means for you. Be sure that your doctor or nurse knows your medical history and whether there’s anything in your history that increases your risk for getting breast cancer.
Any woman who’s already in a high-risk group (based on gene mutations, a strong family history of breast cancer, or other factors) should have an MRI along with her yearly mammogram.
For more information on breast cancer risk factors and whether you’re in a higher-risk group for breast cancer, please call your American Cancer Society at 1-800-227-2345. No matter who you are, we can help. Contact us anytime, day or night, for cancer-related information and support. Visit www.cancer.org, or call us at 1-800-227-2345.©2015, American Cancer Society, Inc. No.004802 - Rev. 7/15
Advocacy, U.S. legislation, and what you need to know.
As of March 28, 2019, the FDA has announced important new steps to modernize breast cancer screening and help empower patients with information when they are considering important decisions regarding their breast health care.
Not all U.S. states are required to notify their patience as to whether or not they have dense breast. As of March 2019, 37 states are required to notify their patience of dense tissue, those the notification process is not standardized. What about the other 13 states? Is your state one of them? Download Data.
Some of our favorite resources regarding this topic can be found below.
Check out our Podcast with Dr. Paula Gordon, a Radiologist from Vancouver on this very topic!