What are dense breasts?

Breasts are made up of milk glands, milk ducts, and supportive tissue (called fibroglandular tissue)—all of which, together, make up the dense tissue in the breast. The nondense element of the breast is fatty tissue. Dense breasts, which are identified on a mammogram, have less fatty tissue, more fibroglandular tissue.

Why do dense breasts matter?

There are steps you can take to minimize your [breast cancer] risk, [including knowing] and understanding your breast density.

Cancer risk

Dense breasts increase your risk for breast cancer. In fact, breast density is one of the top risk factors for breast cancer.

Other breast cancer risk factors include older age; family history; reproductive history (early menstruation start, late menopause, first pregnancy after age 35); obesity; and alcohol consumption.

Screening problems

Dense breasts can cause difficulty for breast cancer screening. When a woman with dense breasts has a mammogram—an x-ray of breast tissue—the results are more difficult to interpret. This is because dense breast tissue and some abnormal breast changes, such as calcifications and tumours, both appear as white areas in the mammogram, whereas fatty tissue appears as dark areas.

How do you know if you have dense breasts?

Women can’t detect the density of their breast tissue through a breast self-exam nor can their healthcare practitioner with a clinical exam, since dense breasts aren’t determined by size or feel. Only a radiologist can determine breast density by examining mammogram results.

Mammograms are an important consideration for women over age forty—even if there is no family history of breast cancer. The best-case scenario is knowing what category of density your breasts are, so that you can make informed decisions with your healthcare provider about what type of breast screening you’re a candidate for and how often.

Screening programs send patients results following their mammograms, which include their BI-RADS assessment (Breast Imaging Reporting and Data System). BI-RADS is used to classify breast density into the following four categories from A to D:

• BI-RADS A: The breast consists almost entirely of nondense fatty tissue.
• BI-RADS B: The breast is mainly nondense fatty tissue with a few scattered areas of dense tissues.
• BI-RADS C: The breast is an almost equal mix of nondense fatty and dense tissue.
• BI-RADS D: The breast is almost entirely dense tissue.

A discussion with your healthcare practitioner is important to determine if you need to, based on your BI-RADS classification and your overall breast cancer risk, seek follow-up screening.

By Dr. Bryn Hyndman

BetsyHealth Note: This article is for educational purposes only. It is not intended to diagnose, treat, prevent or cure any disease. Consult your healthcare provider before trying a supplement, especially if you have a medical condition, including being pregnant or nursing, take prescription or over-the-counter medications, or are planning on having surgery.

Article copyright 2026 by Alive Publishing Group, Inc.