I've been told I have dense breasts. Now what?

Heather Shannon, MS, CNM, WHNP, MPH

You just got call from your provider who informed you that your mammogram is normal, but you have dense breasts and should have additional imaging. Immediately a series of questions race through your mind: ‘What does that mean? Should I be worried? Does this increase my risk for cancer? I always thought my breasts were firm and heavy. Is that why I have dense breasts?’ Let’s get familiar with dense breasts and what it means for you.

What are dense breasts?

To help understand dense breasts, let’s discuss our breast tissue make up. According to Breastcancer.org, normal breast tissue composition can be fibrous or connective tissue, glandular tissue and fatty tissue. A woman who has dense breast tissue has more fibrous and glandular tissue than fatty tissue. We also call this type of tissue, fibroglandular. You may have heard of this before. Fibroglandular tissue is normal and not considered a medical condition. You cannot feel dense breast tissue with your hands nor is it determined by the heaviness or firmness of your breasts.

This type of tissue is can only be seen on mammogram.

When you have dense breast tissue, it is difficult for the mammogram rays to penetrate or see through the entire breast. What does that mean? Dense breast tissue may hide small cancer masses reducing early detection of breast cancer. It does not mean you have breast cancer nor does it cause breast cancer. It means it is harder to detect potential cancer masses with mammogram alone. In addition, the denser your breast tissue is, the greater the chance a cancer can be missed. When your provider gets the mammogram report, it will grade the denseness of your breasts and if you have dense breast, your provider will discuss options to any additional testing needed.

How does the radiologist know how to grade your breasts?

According to the National Cancer Institute (NCI, 2021), breast thickness or density is measured through a mammogram base on images and is categorized by the American College of Radiology as Breast Imaging Reporting And Data System (BI-RADS). The radiologist uses this to categorize the level of density and abnormal findings and rates them from A-D: See Figure 1. Dense breast tissue is seen as white areas on a mammogram, where fatty tissue is seen as dark areas. For about half of women, screening mammograms show they have breast tissue that is categorized as dense. Dense breast tissue can obscure breast cancers on a mammogram and increases the chance that it might be missed. A score of C or D are classified as having dense breasts.

The radiologist makes the classification or a judgment call, which could be different from another radiologist reading the report. For this reason, many breast imaging centers will use additional software to assist with evaluating breast density.

Who is at risk for dense breasts?

Women who are premenopausal, on hormone therapy or have a lower body mass index (BMI) tend to have denser breasts compared to women who are postmenopausal and have children. This does not mean that if you are on hormones, you will automatically develop dense breasts. It does mean it is important that you continue with your breast health by doing regular self breast exams, completing an annual clinical breast exam by your health care provider and getting your mammogram, age appropriate.

One question you might have is does dense breasts make it harder for you to feel abnormal lumps. The answer is no. You will be able to feel abnormal lumps when you do your breast exam. Remember, the only way to know if you have dense breasts is through mammogram screening.

If you have dense breasts, talk to your doctor to discuss your individual risk level based on the amount of dense tissue you have and the necessary monitoring needed. Keep in mind, other breast cancer risk factors such as your personal health history and family history of breast cancer are important to consider. SWM

Heather Shannon is a certified nurse midwife and women’s health nurse practitioner at Oswego County Opportunities. She has a master of science and a master of public health degree.

Figure 1. From Left to Right: BI-RADS categories A through D A) Mostly fatty (10% women): The breasts contain very little fibrous and glandular tissue and are primarily made out of fat. B) Scattered fibroglandular densities (40% women): The breasts are mostly fatty tissue, but there are a few areas of fibrous and glandular tissue visible on the mammogram. C) Heterogeneously dense (40% women): A mammogram shows many areas of fibrous and glandular tissue. D) Extremely dense (10% women): The breasts have large amounts of fibrous and glandular tissue. (Breast cancer.org)