Why Does Breast Density on a Mammogram Matter?

About Breast Density & Why It Matters

Breast tissue is made up of two main components: fibroglandular tissue and fatty tissue. Breast density describes how much of each type is present in your breasts, as seen on a mammogram. There are four classes of breast density:

• Class A: Almost Entirely Fatty
  • Description: This type shows mostly fatty tissue, with very little fibroglandular tissue. Mammograms usually appear clearer.
• Class B: Scattered
  • Description: This type has a mix of fatty and fibroglandular tissue. There is more breast tissue than in Class A, but not as much as in Class C or D.
• Class C: Heterogeneously Dense
  • Description: This type has more fibroglandular tissue, making it harder for doctors to interpret the mammogram. It may hide some areas of concern.
• Class D: Extremely Dense
  • Description: This type has very little fatty tissue and a lot of fibroglandular tissue. Mammograms can be challenging to read.

So, why is this important? Dense breast tissue can make mammograms harder to read. Additionally, having dense breasts may increase the risk of developing breast cancer in the future.

There has been increased recognition of the importance of breast density. Since 2014, breast imaging centers have been required to inform patients if their breast tissue is dense (Class C or Class D) based on MQSA (Mammography Quality Standards Act and Program) guidelines. New guidelines now also require that patients know if their breast tissue is not dense (Class A or Class B) per recommendation from the DPH (Department of Public Health). This means patients should receive clear information about their specific breast density.

It’s essential for patients to talk with their healthcare providers about their breast density, personal risk for breast cancer, family history, and any individual concerns. Understanding breast density helps raise awareness. For some individuals with dense tissue, doctors may recommend additional imaging tests along with mammograms to better detect cancer. Keep in mind that some insurance plans may not cover these extra tests solely based on breast density, so it’s crucial for patients to discuss their overall risk with their provider. 

For more information about breast density, you can visit Dense Breast Information.

At Lahey Hospital and Medical Center, we have a Comprehensive Breast Health Center dedicated to individuals at high risk for breast cancer. Our breast imaging department also offers additional screening options for those with dense breast tissue. Patients are encouraged to discuss these options with their provider.