Breast Density: Are You Informed?

Imagine this: you’ve just received the results of a routine mammogram and the report states that you have dense breasts. But what does that really mean? What exactly are dense breasts and could they be linked to breast cancer? Does having dense breasts increase the risk of developing breast cancer? You might have many questions swirling in your mind about the term “dense breasts.” It does sound confusing, but this article will provide all the information you need to understand breast density. Awareness of this information is crucial as nearly half of the women above 40 have dense to extremely dense breasts. Understanding breast density and its effects on your risk of breast cancer is essential to your health.

Breasts are made up of glands, nerves, blood vessels, connective tissue (ligaments) and fat tissue, and different people have different proportions of these components. Breast density is categorized into four groups:

• Fatty

The breast is mostly composed of fat tissue, making it less dense.

• Scattered

There is a mix of fibrous and glandular tissue with some fatty tissue.

• Heterogeneously dense

The breast has a significant amount of fibrous and glandular tissue with limited fatty tissue.

• Extremely dense

The breast consists mostly of fibrous and glandular tissue, with very little fatty tissue.

Dense breasts have relatively lesser amounts of fat tissue and higher amounts of glands and fibrous connective tissue.

The dense area of the breast appears white and opaque on a mammogram, while the fatty areas appear dark and more translucent (see image below). It is more difficult to visualize abnormal breast lesions (which are also white on the mammogram) in these dense areas.

Breast density is largely determined by genetics, but it can also be affected by age, menopause status and medications.

Now, let’s delve deeper into the association between breast density and the likelihood of developing breast cancer.

Women with dense breasts have an increased chance of developing breast cancer compared to women with fatty breast tissue. This, in addition to the difficulty of detecting cancer in dense breasts via a mammogram compared to women with fatty breast tissue compared to fatty breasts, has led to suggestions of supplementing the mammogram with additional imaging tests in women with dense breast tissue.

Since 2015, studies have suggested additional breast cancer screening for women with dense breasts. Even so, the U.S. Preventive Services Task Force (USPSTF) concluded that there is insufficient evidence to recommend any adjunct screenings to women with dense breasts on an “otherwise negative screening mammogram.” Experts worry that such a recommendation could cause overdiagnosis, leading to overtreatment of false negative cases and increased unnecessary healthcare costs.

Mammography is done yearly or every two years for women aged 40 and above, as the USPSTF and National Comprehensive Cancer Network (NCCN) recommends.

In addition to mammograms, data is supportive of adding supplemental breast imaging studies such as whole breast ultrasound, molecular breast imaging or contrast-enhanced mammogram for women with dense breast tissue, to aid in the detection of breast cancer. Breast MRI is recommended, in addition to mammography, for women at high risk for breast cancer based on a strong family history of breast cancer. Since 2019, many states in the US have required women undergoing mammography to be informed whether they have dense breasts. However, it is also important to note that breast density is just one of several risk factors for breast cancer, and many other factors also contribute to an individual's overall risk.

Learn more: Breast Cancer Risk Factors

If you have dense breasts, it is important for you to be aware of your increased risk and to discuss with your healthcare providers about the appropriate breast cancer screening and risk reduction strategies. This might include more frequent mammograms, additional imaging modalities (e.g., breast ultrasound or MRI), or other risk-reducing measures based on your overall risk profile. Regular breast cancer screenings and early detection remain critical for improving outcomes in women with dense breast tissue or other risk factors.