Dense Breast Tissue

Overview

What is dense breast tissue?

Dense breast tissue refers to the amount of fibroglandular and fibrous connective tissue that’s present within your breast as compared to fatty tissue. When there’s more glandular and fibrous tissue than fatty tissue, your breast is considered dense. Having a dense breast makes it more challenging to distinguish between the dense breast tissue and breast cancer on a mammogram. Both dense breast tissue and potential cancers appear as a white spot on a mammogram. Having dense breasts is common.

What are the parts of the breast?

Your breasts are made of three kinds of tissue:

  • Fibrous connective tissue: Supports, protects and holds your muscles and tissues in place. It appears white on a mammogram.
  • Fibroglandular tissue: Made up of your glands (responsible for making milk) and ducts (tubes that carry milk to your nipple). It also appears white on a mammogram.
  • Fatty tissue: Fills the space between the fibrous tissue and fibroglandular tissue. Fatty tissue is dark or see-through on a mammogram.

Why does breast density matter?

Breast density matters because:

  • Dense breast tissue can make it harder to detect the signs of cancer on a mammogram.
  • It could increase your risk for breast cancer. Research has shown that extremely dense breast tissue puts you at four times the risk for breast cancer compared to fatty tissue.

What are the different categories of dense breast tissue?

Breast density is divided into four types, ranging from having very little dense tissue to extremely dense tissue. The four categories are:

RankClassificationDescriptionPrevalence
AMostly fatty tissueYour breast tissue is almost entirely fat.About 10%
BScattered fibroglandular breast tissueYou have a mix of dense and fatty tissue, but the majority is fatty.About 40%
CHeterogeneously dense breast tissueYou have a mix of dense and fatty tissue, but the majority is dense.About 40%
DExtremely dense breast tissueYour breast tissue is almost all dense.About 10%

If your breast tissue is mostly fatty (A) or scattered fibroglandular (B): You have low breast density, and cancer is more likely to be visible on a mammogram.

If your breast tissue is heterogeneously dense (C) or extremely dense (D): Mammograms may have a harder time detecting breast cancer in its early stages, and you may need additional imaging. This is considered high breast density.

How common are dense breasts?

Having dense breast tissue is common. About 50% of women and people assigned female at birth (AFAB) have dense breast tissue.

What should I do if I have dense breast tissue?

Having dense breasts is something to discuss with your healthcare provider. It needs to be taken in context of other breast cancer risk factors. Your provider may recommend or offer supplemental imaging.

Symptoms and Causes

What causes dense breast tissue?

Dense breasts are more common if you:

  • Use hormone replacement therapy (HRT): People taking hormone replacement therapy to treat symptoms of menopause are more likely to have dense breasts.
  • Have a lower body weight: People with a low body mass index (BMI) may be more likely to have dense breast tissue.
  • Are younger: Your breasts tend to be denser when you’re young and less dense as you get older.
  • Have a family history: Breast density may be genetic, which means you may have a similar density as your biological family.

Diagnosis and Tests

How is dense breast tissue diagnosed?

Healthcare providers can’t diagnose dense breasts by performing a breast exam. Firmer breasts don’t mean you have dense breasts. Only mammograms can reveal how dense your breasts are.

The radiologist reading your mammogram is required to describe your degree of density. The dense glandular tissue will look white, and fatty tissue will look dark on your mammogram. The more white areas the radiologist sees on the image, the denser your breast.

What tests might be offered if I have dense breast tissue?

  • Digital breast tomosynthesis (DBT): DBT or 3D mammography captures several images of your breasts from multiple angles. These images are compiled to create a 3D image of your breasts. This produces images of your breast in layers, making some abnormalities easier to see. It exposes you to more radiation than a standard 2D mammogram, but it’s still below the limit set forth by the FDA (Food and Drug Administration). It detects 25% to 40% more breast cancers.
  • Breast ultrasound: Ultrasound uses sound waves to create pictures of your breast tissue. It can detect several breast cancers, but the false positive rate is high.
  • Breast MRI: Magnetic resonance imaging (MRI) is the most sensitive way to detect breast cancer at its earliest stages. People with a high risk of breast cancer may receive screening with an MRI in addition to a mammogram.

Each type of imaging has its pros and cons. For instance, while MRIs and ultrasounds can identify cancers that mammography misses, they can also mistake noncancerous cells for cancerous ones (a false positive). Your healthcare provider can talk to you about your options and what they recommend based on your risk for breast cancer and the results of your mammogram.

Does breast density change over time?

Breast density can change throughout your life. Some people’s breasts become more fatty (less dense) as they get older, but some people may have no change in their density.

Management and Treatment

Can you change your breast density?

The only way to decrease the density of your breast tissue is to take preventive tamoxifen, a medication reserved for people at increased risk for breast cancer.

Care at Cleveland Clinic

Prevention

Why is dense breast tissue associated with a higher risk for cancer?

Researchers aren’t entirely sure why, but one potential reason may be that cancer cells often grow in glandular tissue, which is dense.

What other risk factors for breast cancer should I be aware of?

Breast cancer is a common type of cancer that affects women and people AFAB. The majority of people who develop breast cancer don’t have any known risk factors. This is why screenings are so important.

Some of the risk factors can include:

  • Family history.
  • Age (risk increases as you age).
  • Personal history of cancer.
  • Having other benign high-risk breast lesions.
  • Drinking alcohol.
  • Childbirth (particularly first child) after age 30.
  • Not having children.
  • Hormone therapy.
  • Having a high BMI.
  • Physical inactivity.

Living With

Do I still need to get mammograms if I have dense breast tissue?

You should still get a mammogram if you have dense breast tissue. Mammograms have been shown to decrease the mortality associated with breast cancer. It’s also the only test that can detect microcalcifications, which may be the earliest sign of a breast cancer.

Discuss both your breast density and your risk factors for breast cancer with your healthcare provider when deciding when to start and how often to get regular mammograms. If you have dense tissue, your provider may suggest a 3D mammogram which has increased breast cancer detection rates, especially in people with dense breast tissue.

Should I be concerned if I have dense breast tissue?

You shouldn’t worry. But if you have dense breast tissue, you should speak with your provider about cancer screening options. About 1 in 8 women and people AFAB will develop cancer in their lifetime. Extremely dense breast tissue is one factor that determines risk. Other risk factors, including your family history and sometimes genetic predisposition, can help determine if you qualify for supplemental breast MRI in addition to a yearly mammogram.

What else can I do if I have dense breasts?

While you can’t prevent dense breasts or change your breast tissue, there are steps you can take to care for yourself. Besides talking to your provider about additional imaging, you can:

  • Get an annual mammogram.
  • Perform breast self-exams.
  • Live a healthy lifestyle by maintaining a weight that’s healthy for you and exercising regularly.

A note from Cleveland Clinic

If you have dense breasts, it means a radiologist may have a harder time detecting cancer on your mammogram. Dense breast tissue is common and normal. Speak with your healthcare provider about your breast density after your mammogram. Get clarity about what your density means. Your provider may recommend additional breast cancer screenings to get a better look at your breast tissue. Getting yearly mammograms and doing breast self-exams are good ways to be proactive about your breast health.

Last reviewed by a Cleveland Clinic medical professional on 11/30/2022.

References

  • American Cancer Society. Breast Density and Your Mammogram Report. (https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/mammograms/breast-density-and-your-mammogram-report.html) Accessed 11/30/2022.
  • Centers for Disease Control and Prevention. What Does It Mean to Have Dense Breasts? (https://www.cdc.gov/cancer/breast/basic_info/dense-breasts.htm) Accessed 11/30/2022.
  • National Breast Cancer Foundation. Breast Anatomy. (http://www.nationalbreastcancer.org/breast-anatomy) Accessed 11/30/2022.
  • National Cancer Institute. Dense Breasts: Answers to Commonly Asked Questions. (https://www.cancer.gov/types/breast/breast-changes/dense-breasts) Accessed 11/30/2022.
  • Radiological Society of North America, RadiologyInfo.org. Dense Breast. (https://www.radiologyinfo.org/en/info.cfm?pg=dense-breasts) Accessed 11/30/2022.
  • The American College of Obstetricians and Gynecologists. Breast Density. (https://www.acog.org/womens-health/faqs/dense-breasts) Accessed 11/30/2022.
  • The American College of Radiology. Breast Density: Breast cancer screening. (https://www.acr.org/-/media/ACR/Files/Breast-Imaging-Resources/Breast-Density-bro_ACR_SBI.pdf) Accessed 11/30/2022.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy