Dense Breasts And Mammograms

If you have dense breasts, you're not alone. About half of all women do, and it can raise concerns about mammograms and breast cancer screening. Indianapolis breast surgeon Jamie Murphy, MD, with Franciscan Physician Network, is here to answer your questions and empower you with knowledge.

What Are Dense Breasts?

Think of your breasts like a mix of fatty and glandular tissue. Dense breasts simply have more glandular tissue, which appears white on mammograms – just like cancer. This can make it harder to spot abnormalities in your breast tissue.

“There's basically four different levels of density that we have broken down into, and it goes from basically completely fatty breasts, which are on one end of the spectrum,” Dr. Murphy said. “On the other end of the spectrum are what we call extremely dense breasts. About 10% of the population is on one end and 10% is on the other end, and everybody else is somewhere in the middle.”

By September 2024, all patients who receive mammograms in the US will receive notifications on their report whether they have dense breast tissue.

Why Does Having Dense Breasts Matter?

While dense breasts don't cause cancer, they can increase your risk for breast cancer and make early detection trickier. That's why mammograms are even more important for you.

“When we really are concerned about density is when we see extremely dense breasts, because we've seen women with that density have a little bit of an increased risk for breast cancer,” Dr. Murphy said. “We don't really know why because it could be twofold. Mainly, is it because of the dense breasts or is it because the radiologists have a harder time looking through the dense tissue to try to find a cancer?

“Because when you look at the mammogram, dense breasts look white, and so do cancers. And so, the breast dense tissue can basically obscure any type of cancer. That is where the 3D mammogram is more important because it can take slices and get thinner, basically, views of the breast to kind of see through the density, if there's any calcifications or masses.”

How Common Are Dense Breasts?

According to the National Cancer Institute, about 40% of women who receive a mammogram have dense breast tissue.

What Mammogram Options Are Available For Women With Dense Breasts?

Standard 2D mammograms are still helpful in detecting breast cancer in women with dense breasts, but the gold standard for dense breasts is 3D mammography (tomosynthesis). 3D mammography takes multiple thin slices, offering a clearer picture and better cancer detection.

“A 3D mammogram becomes more sensitive as the breast density increases,” Dr. Murphy said. “There was a German study that looked at this. They looked at 100,000 women and they looked at the cancer detection rates between 2D and 3D mammogram. They found that as breast density increases, the 3D mammogram becomes more sensitive at detecting invasive breast cancers. So, it has now become the standard for the screening mammogram to be a 3D mammogram or tomosynthesis.”

How Often Should Women With Dense Breasts Have Mammograms?

“I generally don't recommend extra screening for women unless they're in that extremely dense category,” Dr. Murphy said. “There's different modalities that we can use for screening. You can have a breast MRI, you can do breast ultrasound.

“In general for the high-risk BRCA1, BRCA2 mutation carriers, we do six-month interval imaging. So every year, you get a mammogram and then six months in between you get an MRI. So, you're getting something every six months.”

What If I Need More Than A Mammogram?

If you have noticed changes in your breasts such as lumps, bumps, nipple discharger or breast pain, diagnostic imaging may also be ordered.

“If you actually have a complaint like a lump or breast pain or whatever, they do what's called diagnostic imaging, where they're taking specific images of an area of concern in addition to whole breast imaging,” Dr. Murphy said. “They have the radiologist read your films that same day while you're there. And if something comes up that they need to further image, they can do it right then and there.”

Your doctor may recommend other breast testing follow-up testing from a mammogram or an alternative screening to a mammogram.

Depending on your density level, age and other risk factors, your doctor may recommend additional screening such as:

• Breast ultrasound: Good at looking for abnormalities hidden by dense tissue.
• Breast MRI: Excellent for high-risk women with extremely dense breasts.

Knowledge is power: The more you understand about dense breast tissue and breast cancer screening, the better equipped you are to make informed decisions about your health.