If you’ve ever been told you have dense breasts, you may be wondering exactly what that means. Breast density is determined by a mammogram — it has nothing to do with how the breast feels or its size.
“About 43% of women who get mammograms have dense breast tissue, so it is very common. Breast density tends to be higher in younger women and may decrease with age, weight gain, or after menopause,” said Nara Judd, MD, Avera breast surgeon and high risk breast cancer specialist.
Dense Breast Tissue
Breasts are made up of two main types of tissue: fatty tissue and fibroglandular tissue (a mix of glandular tissue and connective tissue). "Dense breast tissue" means there is more fibroglandular tissue relative to fatty tissue in the breast.
How Is Breast Density Classified?
Radiologists classify breast density into four categories:
- Category A — Almost entirely fatty. Very little dense tissue.
- Category B — Scattered fibroglandular density. Some areas of dense tissue, but mostly fatty.
- Category C — Heterogeneously dense. Much of the breast is dense tissue.
- Category D — Extremely dense. Nearly all of the breast is dense tissue.
Categories C and D are considered "dense breasts." If your mammogram report says you have dense breasts, you fall into one of these two categories.
Why Does Breast Density Matter?
Dense breast tissue matters for two reasons:
- It can hide cancers on a mammogram. Both dense tissue and cancers appear white on a mammogram, making it harder to spot a tumor. Think of it like trying to find a snowball in a snowstorm.
- It is linked to a higher risk of breast cancer. Women with very dense breasts have moderately elevated risk of developing breast cancer compared to women with fatty breasts. However, most women with dense breasts will never develop breast cancer. This risk dissipates as breast density decreases.
What Should You Do If You Have Dense Breasts?
- Continue getting your annual mammogram. Mammography is still the most important screening tool for breast cancer, even for women with dense breasts. Ask about 3D mammography (tomosynthesis), which can improve cancer detection and reduce false alarms.
- Talk to your doctor about your overall risk. Breast density is just one factor. Your doctor will also consider your family history, personal history, age, and other factors to determine your overall breast cancer risk.
- Ask about supplemental screening. Depending on your breast density category and other risk factors, your doctor may recommend additional tests such as:
- Contrast-enhanced mammography (CEM) — A newer type of mammogram that uses contrast dye to highlight areas of concern. CEM is safe, efficient and less expensive than MRI.
- Breast MRI — Uses magnets and a different type of contrast dye to create detailed images. May be used if patient cannot have contrast or for further imaging.
- Ultrasound — Used to investigate focal symptoms or mammographic abnormalities
- Be aware of your breasts. Know what is normal for you and report any changes — such as a new lump, skin changes, nipple discharge, or pain — to your doctor right away.
Can Breast Density Change?
Yes. Breast density can change over time. It may change from one mammogram to the next. Factors that are associated with increased breast density are:
- Younger age
- Lower body mass index
- Use of hormone replacement therapy for menopause
Key Takeaways
- Dense breast tissue is common and normal — it is not a disease.
- Dense tissue makes mammograms harder to read and is associated with a modestly higher breast cancer risk.
- You should still get regular mammograms.
- Talk to your doctor about whether additional screening tests are right for you based on your individual risk factors.
If you have questions about your breast density or screening options, please talk to your doctor or the radiology team at your next visit. If your lifetime risk for breast cancer is >20% you may also be a candidate for the Avera High Risk Breast Clinic.
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