Your breasts are made up of glands, ducts and fibrous tissue, referred to collectively as fibroglandular tissue, and fatty tissue, all wrapped in skin. During a mammogram, your radiologist evaluates the images to determine the amount of dense versus fatty tissue in your breasts.
The four breast density scores are:
A — The breasts are made up of almost all fatty or non-dense tissue
B — The breasts contain scattered areas of dense tissue but have a larger percentage of fatty tissue
C — The breasts have a larger percentage of dense tissue than non-dense tissue or heterogeneous density
D — The breasts are primarily comprised of extremely dense tissue
If more than 50 percent of your breast tissue is dense, you are considered to have dense breasts, receiving either a C or D breast density score. Dense breast tissue is common, in fact, approximately 40 percent of women have a C or D score, and dense breast tissue is not abnormal.
You may wonder why the density of your breasts matters. Dense breast tissue makes it more difficult to detect tumors, and slightly increases your risk of developing breast cancer. Detection is more difficult because both dense tissue and tumors appear white on mammography imaging. Advancements in screening technology, including 3D mammography, allow radiologists to examine breast tissue with greater accuracy than ever before, but there is still no test that can detect breast cancer with 100 percent accuracy, especially for those with dense breasts where additional screening tests may be helpful.
A study conducted in November 2012 by the Radiological Society of North America, found that more than 75 percent of women didn’t know their breast density score, but many of the women indicated they would seek additional screenings if they knew they had dense breasts. In order to improve awareness of breast density and ensure women are aware of their breast density score, Illinois passed legislation effective January of 2019, requiring mammography providers to notify women with C or D density scores. You can also read your breast density in your mammogram report in MyChart.
If you are assigned a C or D score, you can speak with your primary care provider about your density and your risk of breast cancer, and discuss other screening tests that may be helpful. Knowing your breast density score, and partnering with your physician to establish a screening schedule that is appropriate for you, will help you take control of your breast health.
To schedule your annual mammography screening, please call 1−630−545−7880.