What Are Dense Breasts?
Your breasts are made up of fatty breast tissue, milk-producing glands and fibrous connective tissue. Dense breasts have more glandular and fibrous tissue and less fatty tissue. About 40 percent of women in the U.S. have dense breasts.
Dense breasts generally do not impact your physical health. However, if you have dense breast tissue, you have to take extra measures to keep your breasts healthy, as having dense breast tissue can increase your risk of developing breast cancer.
Most women inherit dense breasts. You can also develop dense breasts over time due to several factors, including:
- Aging
- Being pregnant or breastfeeding
- Having a low body mass index
- Taking hormone replacement therapy
There’s a strong relationship between progesterone and estrogen—the female reproductive hormones—and breast density. Progesterone, specifically, plays an important role in tissue formation. Women with high progesterone levels have a higher risk of developing dense breast tissue.
Signs of Dense Breasts
Only radiologists can diagnose dense breast issues, and they do so by looking at a mammogram—a type of X-ray screening for breast cancer. You may think you have dense breasts if yours feel lumpy, heavy or have a rope-like texture, but this isn’t always true.
How Is Breast Density Measured?
When you have a mammogram, your radiologist reports the findings using BI-RADS, which stands for Breast Imaging Reporting and Data System. The reports provide a number from 0 to 6 that tell your doctor whether they found a suspicious area. It also tells your provider if you have dense breast, using a letter system from A to D.
- A (mostly fatty): Mostly fatty tissue with very little fibrous and glandular tissue
- B (scattered fibroglandular densities): Mostly fatty but with areas of dense breast tissue
- C (heterogeneously dense): Many areas of the breasts have fibrous and glandular tissue
- D (very dense): This means your breasts have a lot of fibrous and glandular tissue
What Dense Breast Tissue Means for Mammograms
Dense breast tissue and cancer can both appear white on a mammogram, making it harder for your radiologist to detect cancer. If you have dense breasts, your doctor might recommend additional screenings.
These tests could include:
- 3D mammography (tomosynthesis): This technology takes multiple images of your breasts from different angles and compiles them to create a 3D view. It can be more effective than standard 2D mammograms at detecting cancers in dense breasts.
- MRI: This uses magnets and radio waves to create detailed images of the breast. It’s the most sensitive screening tool but is typically reserved for women at high risk of developing breast cancer.
- Breast ultrasound: This uses sound waves to create images of breast tissue. It can help detect tumors that may be hidden in dense breasts.
What to Do If You Have Dense Breasts
If you’re worried you have dense breasts, talk to your provider about ways to protect your breast health.
If you’ve had a mammogram and your provider diagnosed you with dense breasts, it’s important to take a proactive role in your breast health to reduce your chances of developing breast cancer by:
- Reviewing your mammogram report. Ask your provider to explain your BI-RADS category in simple terms. If you fall under categories A, B, C or D, have them explain what this means and the next steps you should take.
- Asking your provider about your screening options. Talk with your provider about additional screenings, such as 3D mammography, an ultrasound or MRI. Your provider will consider other factors, such as your family history of breast cancer and your current health status, when determining further screening.
- Keeping up with regular screenings. While dense breasts can make mammograms more challenging, they remain very important. Stick to the personalized screening plan your provider recommends, including any supplemental tests they suggest.
- Regularly checking your breasts. Become familiar with how your breasts usually look and feel. Promptly report any changes, such as lumps, breast pain or nipple discharge, to your provider.
More to Read
- Advice for Women Who Are At High Risk for Breast Cancer
- What You Need to Know About Breast Cancer in Younger Women
- Tips to Optimize Breast Health
- How Exercise Helps Breast Cancer Prevention and Recovery
- Genetic Testing for Breast Cancer
- Find a Lump in Your Breast? What to Do Next
Medically reviewed by Cynthia L. Drogula, MD.
