Cedars-Sinai Blog
What Does It Mean to Have Dense Breasts?
About half of women aged 40 and older have dense breasts. Unfortunately, many women don’t know whether their breast tissue is dense, or that having dense breasts is linked to a higher risk of cancer.
Soon that may change thanks to new regulations mandating healthcare providers to inform patients about their breast density after they receive mammograms. The Food and Drug Administration regulations, which took effect in September 2024, aim to ensure women understand the cancer risk associated with breast density.
Dense Breasts Explained
Breast tissue is made up of glandular tissue, fibrous (connective) tissue and fat. Dense breast tissue has larger amounts of glandular and fibrous tissue and lower amounts of fatty tissue.
“The only way to determine if you have dense breast tissue is by getting a mammogram,” said Cynthia Litwer, MD, chief of breast imaging at Cedars-Sinai.
Cynthia A. Litwer, MD
Based on the images produced during a mammogram, doctors categorize breast density into four levels:
- Almost entirely fatty: minimal dense breast tissue
- Scattered areas of fibroglandular tissue: mostly fatty tissue with scattered areas of dense tissue.
- Heterogeneously dense: predominantly dense with some areas of fatty tissue
- Extremely dense: nearly all dense tissue with very little fat
If your breast tissue is classified as heterogeneously dense or extremely dense, you have dense breasts.
Factors Linked to Dense Breasts
Dense breasts are usually genetically linked, meaning you inherit breast density from one of your parents. Other factors linked to higher breast density include:
- Young age
- Low body mass index
- Taking hormone replacement therapy
“The only way to determine if you have dense breast tissue is by getting a mammogram. That’s why we encourage women to get a baseline screening mammogram at age 40.”
Dense Breasts and Cancer Risk
Women who have extremely dense breasts face a two- to three-fold increased risk of breast cancer compared to those with almost entirely fatty tissue. To complicate matters, dense tissue makes detecting breast cancer more difficult. Both dense breast tissue and abnormal changes in the breast show up as white on a mammogram—unlike fatty tissue, which is transparent.
“If you have dense breasts, mammograms should still be part of your breast health evaluation,” Litwer said.
At Cedars-Sinai, advanced mammography technology called digital breast tomosynthesis, or 3D mammograpy, provides detailed, three-dimensional images of breast tissue. This allows radiologists to zoom in on concerning areas and reduces false positive rates compared to traditional 2D mammography.
AI tools also help radiologists spot abnormal tissue on 3D mammography images.
Caring for Dense Breasts
Learning you have dense breasts can be distressing, but having dense breasts, even though it is associated with a higher cancer risk, doesn’t increase your risk of dying of the disease.
If your mammogram report states you have dense breast tissue, it’s important to discuss that finding with your referring doctor and inquire about whether you might benefit from additional screening, such as:
- Breast magnetic resonance imaging (MRI), which uses magnetic field and radio waves to create 3D images of breast tissue
- Breast ultrasound, which uses sound waves to differentiate between solid masses and fluid-filled sacs
- Contrast enhanced mammography, which uses contrast material to highlight areas of concern on a traditional mammogram
“Some U.S. senators are advocating for national coverage for ultrasound, MRI and other supplemental breast imaging for patients with dense breasts,” Litwer said. “But every woman, no matter her breast cancer risk, should get a baseline mammogram at age 40.”
If you have a first-degree family member who has had breast cancer, or if you carry an inherited genetic mutation linked to the disease, you may need to start screening before age 40.
Doctors also advise talking to your primary care provider to create a personalized breast cancer screening plan tailored to your unique risk profile. You can also take steps to safeguard your breast health by eating a whole-foods diet, exercising regularly, getting sufficient sleep and limiting alcohol consumption.
