• Cancer

    Mayo Clinic Minute: What does it mean if you have dense breasts?

Mammograms are better at detecting cancer in women who do not have dense breasts. How do you know if you have dense breasts, and what does it mean if you do? Dr. Loni Neal, an internal medicine physician at the Mayo Clinic Breast Diagnostic Center, explains what dense breasts are and why it matters.

Watch: The Mayo Clinic Minute

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Mammography is a screening tool to help detect breast cancer. It can also determine if you have dense breasts. Dr. Loni Neal says breast density has nothing to do with size.

"Breast density refers to the relative proportion of fatty tissue – versus glandular or fibrous tissue – when viewed on a mammogram."

Without a mammogram, you can't see the difference. And you can’t feel the difference either.

"Fatty tissue appears black on a mammogram, whereas the milk glands and fibrous tissue of the breast appear white," says Dr. Neal.

If a mammogram shows more white than black, you have dense breasts.

"The more white there is, the more dense your breast is," says Dr. Neal.

What does it mean if you have dense breasts? It means that mammograms may not clearly reveal some cancers, because tumors also appear white. If you have dense breasts, talk to your health care provider about which breast cancer screening tool is right for you.