Dense breasts and cancer: Tips to empower you and improve your breast health

Standard mammograms are an optimal screening tool to find breast cancer in most patients. When breast radiologists review the mammogram results, they can see the ratio of dense to non-dense breast tissue and assign a category of breast density. If the category is dense breasts, then it’s important for the patient to learn more about the condition, as it poses an increased risk for breast cancer.

What are dense breasts?

All breasts are made up of glandular tissue and fatty tissue, plus fibrous tissue that holds everything together. Dense breasts have a higher proportion of glandular tissue than fatty tissue.

There are four categories of breast density:

A: Almost entirely fatty, with less than 25% of glandular tissue.

B: Scattered areas of fibroglandular density, with 25-50% of glandular tissue.

C: Heterogenously dense, with 50-75% of glandular tissue.

D: Extremely dense, with more than 75% of glandular tissue.

Dense breasts are common. Most patients – 80% - fall into either the B or C categories. The denser the breasts, the harder it is for radiologists to spot cancer on a standard mammogram.

How do dense breasts increase breast cancer risk?

Having dense breasts inherently increases the risk for breast cancer by two to four times. In a mammogram, which is a black-and-white X-ray of the breast, non-dense breast tissue appears black and transparent. Dense breast tissue appears as a white area. Breast masses and cancerous tumors are also white, making them sometimes difficult to spot. Since dense tissue can mask potential cancer, a mammogram might not be enough for cancer detection and supplementary tests may be necessary.

Will I be told if I have dense breasts after a mammogram?

Yes. Federal notification laws are sweeping the nation. In Illinois, not only is it required to inform patients that they have dense breasts, but insurance companies are required to cover a supplemental screening exam for patients with dense breast tissue.

If I have dense breasts, what are my options for breast cancer screening?

People with an average risk of breast cancer should start getting annual screening mammograms starting at age 40. Those with dense breasts can benefit from tomosynthesis, which is a 3D mammogram that uses X-rays to collect multiple images of the breast from several angles. The images are synthesized by a computer to form a more detailed 3D image of the breast. The other two options for supplemental screening are a whole breast ultrasound examination or a breast MRI.

What are some of the drawbacks to these different tests?

Many people have anxiety about getting a mammogram because the breast is compressed during the examination. We do this to reduce its thickness and use less radiation to get a good picture. At some of UChicago Medicine’s mammogram testing sites, we have a newer technology with smart curve paddles and that technology greatly reduces the compression associated with a mammogram.

If all of these tests are covered by insurance in Illinois, which one should I get?

In this era of personalized medicine, we have all these amazing tools and we want to pick the right one for you. Talk to your radiologist about what would be the most appropriate test for you and your risk status. If you already have documented dense breast tissue on a prior mammogram, you should consider getting a 3D mammogram on your next screening mammogram and perhaps supplement it with a whole breast ultrasound or breast MRI. The key is to understand your risks and know that there are tools to perform the correct test for you.

What causes dense breasts?

The biggest factors are age and genes. Younger females with estrogen in their body traditionally have denser breast tissue. Also, if your mom had dense breast tissue, you’re more likely to have it. Dense breasts have nothing to do with body weight or build. After menopause, breast density usually decreases as estrogen decreases.

Can you figure out on your own if you have dense breasts? Are they the same as firm breasts?

Unfortunately, that is not possible. Physical examination does not help determine breast density, as dense breasts are not the same as firm breasts. A mammogram is needed.

How do dense breasts affect self-exams?

Breast self-exams are no longer included in the federal guidelines. What matters is getting comfortable with what your breasts feel like. No breast feels the same. What you’re looking for is a change. If all of a sudden you feel a ball or a mass you’ve never felt before, that’s something you need to bring to the attention of your doctor.