Understanding Breast Tissue Density

Getting a mammogram is never fun, and the wait time between completing your scan and receiving your results  can be stressful, but this exam is an essential part of every woman’s routine health and wellness checkup. Simply put, it needs to be done because mammograms save lives.

Nobody ever wants to have their mammogram report come back with anything other than an “all clear,” and this fear can make it easy to put this test off. But not everything listed on a mammogram report needs to be so overwhelmingly concerning.

One of the most common of these discoveries is “dense breast tissue.” Seeing these words on your mammogram report can naturally cause all manner of questions to pop into your head, but just what does this term mean? Is it something to worry about? Does it increase your chance for breast cancer?

In this post, we’ll take a deep dive into breast tissue density to answer these questions and others. This way, if you see “dense breast tissue” on your next mammogram report, then you’ll have a better understanding of what it actually means.

What is Dense Breast Tissue?

Before we discuss dense breast tissue, it is important to understand what breasts are actually made up of. Breasts are made up of lobules, ducts, and connective tissue, which can be both fatty and fibrous.

The lobules are the glands that are responsible for producing milk and the ducts are the tiny network of tubes that deliver the milk from the lobules to the nipples. Combined, the lobules and ducts make up the breast’s glandular tissue. The fatty and fibrous connective tissue is what holds the breast’s structures in place, and this is what gives breasts their size and shape.

According to the American Cancer Society, when a breast has less fat than it does fibrous and glandular tissue, it can be difficult to see the fibrous and glandular tissues through the mammogram’s imaging. When this is the case, the breast tissue is usually recorded as being “dense.” So, when you see the term “dense breast tissue” on a mammogram report, it means that the breast imaging isn’t as clear as it should be because the breast doesn’t have much fat.

How Do Radiologists Determine Breast Tissue Density?

According to the Mayo Clinic, when a radiologist or physician reviews your mammogram’s images, they are looking for any signs of abnormalities, but breast density is also something they are looking at. Your breast density will be categorized as either Category A, B, C, or D. The following is a brief overview of what these categories mean:

• Breast tissue that falls under Category A consists of almost all fat tissue. This means the breast has very low tissue density. Fat shows up as black on mammogram images, which makes reading the images and identifying masses substantially easier because masses show up as white.
• Category B breast tissue shows up on the images with scattered areas of more fibrous connective and glandular tissues. These tissues appear as white areas on the mammogram images because they are denser than fat.
• Category C is reserved for breast tissue that has more fibrous connective and glandular tissues than it does fat. This type of breast is considered to be heterogeneously dense, and this can make it more difficult to see small masses in the areas with the most dense tissue because both the tissue and the masses appear white.
• Category D is used to categorize breasts that largely consist of extremely dense tissue. Breasts that fall under this category can make it especially hard to identify masses in the mammogram images.

Is Dense Breast Tissue Common?

 It is not uncommon for women to have dense breast tissue. In fact, about half of all women in the United States who have mammograms fall under either Category C (heterogeneously dense) or Category D (extremely dense), so they are considered to have dense breast tissue.

 One reason for dense breast tissue being so common is that it can often be a simple case of genetics. If a mother has dense breast tissue, then the odds are high that her offspring will too. Plus, there are also other external factors that can affect breast tissue density. For instance, those who receive menopausal hormone therapy or who have a low body mass index can have a higher prevalence of dense breast tissue.

On the other side of the scale, a lot of patients will see their breast tissue density decline as they age and/or after they have children. As a result, dense breast tissue is most common in younger adults and among those with a family history of having it.

Is Breast Tissue Density Required on Mammogram Reports?

When mammogram reports are sent to health care providers, they almost always include a description of the breast tissue density following the category system mentioned earlier in this article. But this is not always the case when mammogram reports are sent directly to patients because the law requiring this information to be included varies by state. However; this will change on September 10, 2024, as all future mammogram reports will be required by law to include the patient’s breast tissue density.

Why is Breast Tissue Density Important?

If you are having a mammogram performed, it is important to know your breast tissue density for a couple of reasons. For one, studies show that patients who are diagnosed with dense breast tissue tend to have a higher risk of breast cancer compared to those with less dense breast tissue. The exact reason for this increased risk is not exactly known, but it is believed that dense breast tissue simply has more cells that can develop into abnormal cells.

Additionally, the denser the breast tissue is, the harder it will be for radiologists to see cancer on mammogram images. Because dense breast tissue appears white on a mammogram, it can be difficult to distinguish the breast tissue from any existing masses and cancers, since these also appear white in the images.

According to breastcancer.org, women with dense breasts are more likely to be diagnosed with breast cancer within a year after their mammogram results came back.

Is It Still Important to Have a Mammogram if I Have Dense Breast Tissue?

At this point, you might be tempted to think – what’s the point of getting a mammogram if I have dense breast tissue? The truth is that most breast cancers can still be seen on a mammogram even in those with dense breast tissue, so having a regular mammogram done is still an essential part of a good health and wellness routine.

Or, there may be other imaging tests that can be performed on those with dense breast tissue if a standard mammogram proves to be inconclusive. These can include a digital breast tomosynthesis (3D mammography), a breast ultrasound, or possibly magnetic resonance imaging (MRI). There are pros and cons to each of these procedures, so talk to your health care provider about whether they believe any of these tests can help improve the accuracy of your examination.

What Should I Do if I Have Dense Breast Tissue?

If your last mammogram report indicated that you have dense breast tissue, you should talk with your physician about what this means for your unique situation. If your family’s medical history increases your risk for breast cancer, then make sure your physician is aware of everything that can play a role in your risk level.

If you have high breast tissue density and are already considered high-risk based on your genetics, a strong family history of breast cancer, or other factors, then you may want to ask your physician about having an MRI along with your yearly mammogram.

Lastly, it is important to remember that a finding of dense breast tissue is not a breast cancer diagnosis. Many women simply have dense breast tissue. Your physician will help you understand what it means to you. Above all, it is most important to know how your breasts normally look and feel, regardless of whether your last mammogram report was normal or indicated high tissue density. Should you ever feel a change, you should contact your physician immediately, so the appropriate testing can be done.