Breast Density and Cancer: Are You at Risk?

Patient Expert

There’s something in your mammogram your doctor’s probably not telling you. And not having this information could potentially put you at risk for cancer.

Breast density: what is it?

What your doctor may not be not sharing with you is your breast density: the balance of fibroglandular tissue to fat in your breasts, easily determined via mammogram.

When that balance tends towards fat, a woman’s breast density is considered low. But when connective, glandular, and fibrous tissue are predominant, a woman’s breast density is considered high.

Why is breast density important?

Density is a breast cancer risk factor. According to the American Cancer Society, women with dense breasts are 4 to 6 times more likely to be diagnosed with breast cancer than those with normally fatty breasts. Only sex (female), age (older), and mutated BRCA genes are stronger indicators of breast cancer risk than breast density.

In addition, a woman’s breast density can lower the effectiveness of her mammograms. Since fibroglandular tissue appears opaque on a mammogram -- just as cancer would -- it can mask tumors, making it hard for radiologists to discriminate between what’s normal and what might need a second look.

How dense is too dense?

There are four categories of breast density. The radiologist looking at your mammogram determines which of the four categories your breasts fall into. S/he notes this information in your mammogram results, communicating it to your doctor. When fibroglandular tissue represents more than 75 percent of the breast, a woman is considered at increased risk for breast cancer.

Once your mammogram is read, the radiologist knows if you have dangerously dense breasts. So will your doctor. Why don’t you?

Issues with dense breast notification (DBN)

A woman’s breast density evolves over the course of her lifetime, so a “diagnosis” of highly dense breasts can change, sometimes over the course of a single year.

In addition, there’s no treatment for highly dense breasts, though women who have them should consider alternate screening methods such as ultrasound or MRI -- options insurance may or may not pay for.

Communicating to a woman that she has dense breasts means scheduling time for a conversation about it, and explaining what steps the woman might take going forward. Doctors are busy; adding another appointment to their schedules is usually problematic. It’s not surprising that physicians aren’t rushing to make DBN part of the annual mammogram.

Lawmakers are responding

Breast density as a breast cancer risk factor is being taken seriously enough that legislation requiring DBN has passed in 27 states, and is pending in eight more. Still, a recent study assessed that of those 27, only three states deliver the information in a form simple enough for the majority of its residents to understand. That typically means in language written to the level of someone with an eighth grade education. So even in those states requiring DBN, chances are the message isn’t being received.

What can you do?

Next time you schedule a mammogram, follow it up with a call to your PCP. Ask that you receive a report on your breast density, along with the results of the mammogram. If you don’t receive DBN, ask for it again. Dense breasts are a significant enough breast cancer risk factor that it’s worth the extra time and effort to determine whether you have them.

Wondering if your state requires dense breast notification? This interactive map shows which states have passed legislation requiring notification (as well as the wording of the notification itself); which have legislation pending, and which haven’t yet acted.

See More Helpful Articles:

Dense Breasts: Avoiding Needless Biopsies

Breast Cancer: Top 10 Risk Factors

Breast Density: Why You Should Care

New Ultrasound Approved for Dense Breast Screening


Kressin, Nancy R. "Content, Readability, and Understandability of Dense Breast Notifications by State." JAMA Network. April 26, 2016. Accessed May 10, 2016.

"Study Finds Readability of Dense Breast Notifications Poor." Boston University Medical Campus. April 26, 2016. Accessed May 10, 2016.

Breast cancer survivor and award-winning author PJ Hamel, a long-time contributor to the HealthCentral community, counsels women with breast cancer through the volunteer program at her local hospital. She founded and manages a large and active online survivor support network.