Breast Density 101: What It Is And What It Means

The worry of ever having to receive a breast cancer diagnosis has probably passed through every woman’s mind at one point or another. This may be in part because of how frequently breast cancer pops up in conversation, and the fact that the majority of people either personally know or know of someone who’s suffered from the disease.Between the stories in the news and the whole month of October being devoted to breast cancer awareness, it feels like breast cancer is everywhere. That aside, the risk isn’t being overstated.

About 1 in 8 women in the U.S. will develop invasive breast cancer in her lifetime. In 2018, an estimated 266,120 new cases of invasive breast cancer are expected to be diagnosed in women in the U.S., along with 63,960 new cases of non-invasive (in situ) breast cancer, according to the American Cancer Society.

Women with dense breasts in particular are 6 times more likely to develop breast cancer during their lifetimes. It’s a statistic that most of us know about, but knowing this isn’t the same as understanding it. Let’s take a look at the facts behind breast density and see what that means for you.

What Is Breast Density?

All breasts are made up of a lobules (glandular tissue), ducts, and fibrous and fatty connective tissue. Breasts with a lot of fibroglandular tissue and little to no fatty tissue are considered dense breasts, which, to the naked eye may appear “firmer,” “tighter,” or closer to the chest.

Breast density can be determined by the radiologist who reads your mammogram. Radiologists tend to classify breast density into 4 categories:

  • Almost entirely fatty (10% women in U.S)

  • Scattered areas of fibroglandular density (40% women in U.S.)

  • Heterogeneously dense (40% women in U.S.)

  • Extremely dense (10% women in U.S.)

What Does Breast Density Mean?

Although it is not clear why, women with dense breasts are more prone to developing breast cancer. At the same time, the fibroglandular tissue in dense breasts makes reading a mammogram more challenging because both fibroglandular tissue and lumps/tumors appear white.

What Does This Mean For You?

Regardless of whether you have dense breasts or not, the best way for determining whether you may be at risk for breast cancer, or developing breast cancer, is a mammogram. Though other imaging technologies, such as MRI’s, can see through the white matter in dense breasts more clearly, they can also show more findings that are not cancer. This may lead to unnecessary and expensive tests that may not be covered by health insurance.

If your radiologist determines that you have dense breasts, the best course of action will probably include monthly breast self-exams, annual breast exams and annual mammograms after the age 40.

Knowing your family medical history and your genetic propensity for developing breast cancer is important to monitoring your health. If you are unsure about whether you may be at risk for breast cancer, schedule an appointment with one of our radiologists and learn all you need to know.

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