You’re dedicated to your monthly self-exams and you follow your healthcare provider’s recommendations for breast cancer screenings, given your age and family risk factors. But when it come to breast density, are you aware of dense breast tissue? An important part of breast cancer prevention is knowing your breast density and taking this into account during screening.

Breast density is a way to describe the composition of a woman’s breasts. It compares the area of breast and connective tissue – as seen on a mammogram – to the area of fat. Breast and connective tissue are denser than fat, so high breast density means there is more breast and connective tissue as compared to fat. On a mammogram, connective tissue appears as solid white, making it difficult to see through. And therein lies the challenge.

“Breast cancer also is white on a mammogram,” said Michael Macon, MD, FACS, Breast Surgeon and Medical Director of the BreastCare Program at Yavapai Regional Medical Center (YRMC). “The whiter the background, the more difficult it is to identify breast cancer in the white background of a dense breast.”

What Causes Dense Breast Tissue?
Generally, women who are younger and thinner have denser breast tissue, according to Dr. Macon. As a woman ages, she may gain weight, decreasing the density. Genetics also plays a role. If your mother had dense breasts, you are more likely to as well.

Additionally, breast density is more common among women taking hormone therapy to relieve the symptoms of menopause. Women with dense breasts have a higher risk – up to six times, by some estimates – of developing breast cancer. The reason is unknown.

Learn Your Breast Density
How can you learn your breast density? The YRMC radiologist administering your mammogram will determine the ratio of your dense to non-dense tissue. Four categories are used in the Breast Imaging Reporting and Database Systems:

  1. Fatty Replaced Breast (Category A, 0-25% dense tissue): This mammogram likely would show any abnormalities.
  2. Scattered Fibroglandular Density (Category B, 25-50% dense tissue): This breast density has quite a bit of fat, but also a few areas of fibrous and glandular tissue. This is the most common category.
  3. Heterogeneously Dense (Category C, 50-75% dense breast tissue): When areas of fibrous and glandular tissue are greater than fatty breast tissue, it can be difficult to see small masses on mammograms.
  4. Extremely Dense (Category D, 75-100% dense tissue): This increases the difficulty of detecting cancerous tissue because it can blend in with other white background tissue.

What Should I Do About Breast Density? Should I Worry About Dense Breast Tissue?
“If the radiologist determines you have heterogeneous density or extreme density, it is important to have a 3-D mammogram,” said Dr. Macon. “A 3-D mammogram uses new technology to create a three-dimensional picture.”

To assess your risk for breast cancer, Dr. Macon recommends the Tyrer-Cuzick Model – also known as the Ibis Risk Model – which is available here. This risk assessment tool generates a 10-year risk and lifetime risk of breast cancer based on your answers to a series of questions, including one about breast density. Women with Category C or Category D breast density have an increased risk for breast cancer.

“For women with a lifetime risk of breast cancer greater than 20 percent,” explained Dr. Macon, “more aggressive breast surveillance consisting of alternating 3-D mammograms and breast Magnetic Resonance Imaging (MRI) is the standard.”

For screening mammography, including 3-D mammography, contact: