Why Breast Density Matters
September 2013

Why Breast Density Matters

Certain factors can raise your risk for breast cancer. Some you probably already know about, such as age and a family history of the disease. But what about breast density? Research shows that not all women have a clear understanding of breast density and its connection to breast cancer. Read on to learn more about this lesser-known risk factor.

Photo of woman at an X-ray machine, getting a mammogram

Breast density basics

A woman's breasts contain a combination of fat and two types of body tissue-breast and connective. Breast tissue refers to the structures in the breast that produce milk and carry it to the nipple. Connective tissue holds everything together.

The amount of tissue versus fat determines breast density. Every woman has a different amount of fat and tissue in her breasts. The proportion is partly genetic. You are more likely to have dense breasts-that is, more tissue and less fat-if a woman in your family also has them.

Breast density can change over time. Younger women often have denser breasts. A woman's breasts usually develop more fat as she ages, especially after menopause. Pregnancy may also lower breast density.

The breast cancer connection

Past studies have found a strong link between breast density and breast cancer. Women with denser breasts may be four to five times more likely to develop the disease. As of now, scientists aren't sure why. Research is ongoing.

Along with a higher risk for the disease, dense breast tissue can make it harder to find cancer with a mammogram. Why? On a mammogram, fat appears dark gray. In contrast, dense breast tissue shows up light gray or white-similar to how cancer looks. This resemblance can hide potential tumors.

Looking at a mammogram, a radiologist can use several scientific methods to determine a woman's breast density. The most common method in the U.S. is called BI-RADS, or Breast Imaging Reporting and Data System. It classifies breast density into four categories, ranging from 1-mostly fatty-to 4-extremely dense. Eighty percent of women fall in the middle two groups.

Many women may not know if they have dense breasts. That may soon change. Since 2009, 11 states have established laws that require health care providers to inform women if they have dense breast tissue. Such legislation pertains specifically to women whose mammogram results fit into the third or fourth BI-RADS categories. With this information, women and their doctors can make better decisions about breast cancer screening and prevention.

Always talk with your health care provider to find out more information.

 

Talking with Your Doctor About Breast Density

Not all women have dense breast tissue. But if you are concerned about it, below are some questions to help you talk about breast density with your doctor:

  • Has my breast density ever been measured?

  • How dense are my breasts?

  • Was the BI-RADS method used to measure my breast density? If not, can you explain which method was used?

  • Along with a regular mammogram, what other screening tests should I consider?

  • Besides breast density, what else may put me at risk for breast cancer?

  • How can I lower my risk for the disease?

 

Take this online assessment to help determine your risk for breast cancer.

Online Resources

American Cancer Society

American College of Radiology - Breast Density: Breast Cancer Screening

Susan G. Komen for the Cure - Breast Density

 

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