Better Me

What Does It Mean to Have Dense Breasts?

No two breasts are alike – even on the same person. Breasts come in varying shapes, sizes and even locations (gravity and age aren’t kind to breasts). However, did you know they come in different densities as well?

You won’t be able to know if you have dense breasts just by looking or feeling necessarily. Dense breasts also don’t have anything to do with heavy or large breasts either.

Read on to learn more about dense breasts, how to determine if you have them, the potential risks and the importance of screenings.

What are dense breasts?

Approximately half of cis women have dense breast tissue, especially young women with a lower body mass index. The density of your breasts can also change throughout your lifetime.

“Your breasts are made up of different tissues, including glands and ducts that function to produce milk and deliver it to the nipple, and structural tissues such as fat, connective tissue and blood vessels that support the glands in the ducts,” said Kelly Rosso, MD, a breast surgical oncologist at Banner MD Anderson Cancer Center in Arizona. “Basically, density is related to the amount of glandular tissue versus the number of fatty tissues that makes up the breast.”

About 10% of women have extremely dense breasts and another 10% have non-dense breasts. The other 80% of women fall somewhere in between.

Why is it important to know if you have dense breasts?

Knowing whether or not you have dense breast tissue is important, because it makes breast cancer screening more difficult, and it increases your risk of breast cancer.

Since you can’t see or feel to know if you have dense breasts on your own, it’s important to get screened via a diagnostic mammogram.

Non-dense areas in the breasts appear dark and transparent on mammogram images. Areas of concern, such as tumors and masses, show up as white. The challenge is that dense breast tissue also shows up as white, which makes your breasts more difficult to screen for cancer.

“The ratio of dense versus non-dense tissue as seen on the mammogram can help the breast imaging specialist or radiologist determine if you have dense breast tissue or not,” Dr. Rosso said. “Many states require that mammogram reports include information about breast density.”

There are four types of breast density, which are determined by a breast specialist or radiologist who is reading your mammogram. Breast Imaging Reporting and Data System (BI-RADS) classification is the most commonly used method. The levels of density are:

  • Category A: Breasts are almost entirely made up of fatty tissue
  • Category B: Breast tissue has scattered areas of fibroglandular density, but the majority is non-dense
  • Category C: Breast tissue is heterogeneously dense (may obscure small masses) with small areas of non-dense tissue
  • Category D: Breast tissue is extremely dense (which may lower the sensitivity of mammography) meaning nearly all the breast tissue is dense

“Categories A and B mean your breasts aren’t dense and you should continue with annual mammograms,” Dr. Rosso said. “Categories C and D mean you have dense tissue and may benefit from additional screening.”

It’s important to note that while your breasts may look slightly different, you almost always have the same breast density in both breasts. “We don’t give separate density designations for the right versus the left breast,” Dr. Rosso said.

If your state doesn’t require breast density to be included on a mammogram report, you can ask your radiologist to tell you your classification.

Should I worry if I have dense breasts?

Dense breasts are normal, but it’s important to keep in mind and to discuss with your provider.

“Breast density is something you can’t really change because it’s influenced by your genetic makeup, body composition, menopausal status and hormone levels,” Dr. Rosso said.

Rather than worry, Dr. Rosso said to be vigilant about your breast screenings and to make lifestyle changes that may decrease your breast cancer risk.

These include:

  • Breastfeeding
  • Limiting alcohol to less than one drink a day
  • Not smoking or quitting smoking
  • Maintaining a healthy weight
  • Exercising at least 150 minutes per week at moderate intensity

Will I need additional screenings if I have dense breasts?

It is recommended that all women begin breast cancer screening with bilateral screening mammograms at the age of 40.

Not all women with dense breasts need additional screening, but if you have a strong family history of breast cancer or other risk factors including smoking, obesity, inactivity or a gene mutation, it is important to your provider when determining whether additional screening is needed.

Additional screening tests may include:

  • 3D mammography (tomosynthesis): Tomosynthesis uses X-rays to collect multiple images of the breast from several angles. The images get pulled together into a 3D image of your breast.
  • Breast MRI: The MRI uses magnets (not radiation) to create images of the breast.
  • Breast ultrasound: Ultrasound uses sound waves to analyze tissue.
  • Molecular breast imaging (MBI) or breast-specific gamma imaging: A special camera is used to record the activity of a radioactive tracer or special liquid that is injected into a vein of your arm. Normal tissue and cancerous tissue react differently to the tracer, which can be seen in images produced by the camera. This tool is not available at every breast imaging center, however.

“If you have dense breast tissue, you may consider 3D mammography, which is better at detecting cancer in dense breast tissue than a traditional mammogram,” Dr. Rosso said. “If you’re at higher risk, additional screenings may include an annual MRI or whole breast ultrasound and annual clinical breast exams by a specialist.”

If there are still concerns after other tests are completed, a biopsy may be suggested.

Bottom line: Annual mammograms are the gold standard in breast cancer screening

Each person’s body and set of breasts are unique, but there is one thing every woman can do to lower the risk of breast cancer—have annual screening mammograms. Mammography remains the gold standard screening technique and offers an effective means to detect breast cancer early.

“Routine mammograms should start at the age of 40,” Dr. Rosso said. “It’s also important to become familiar with how your breasts normally feel and look. Pay attention to changes, including new lumps, skin thickening or leakage from the nipples.”

Though you can’t change the density of your breasts, being aware of your density can help you and your health care provider make informed choices about your care.

To find a Banner Health specialist near you, visit

Related articles:

Breast Cancer Cancer Women's Health