What and why every woman needs to know about dense breasts

Reviewed by James Ives, M.Psych. (Editor)Dec 17 2019

Two new state laws targeting breast cancer screenings and dense breasts have been passed in Illinois since 2018. Still, many women don't know whether they have dense breasts and how that affects breast cancer screenings -; despite roughly half of all women having dense breast tissue. We spoke with oncology radiologist Deepa Sheth, MD, who specializes in breast imaging at the University of Chicago Medicine, to explain what dense breast tissue means and why it matters.

What are dense breasts, and why should women know whether they have them?

It's a term used to describe breasts that have a higher proportion of glandular tissue to fatty tissue. We get worked up about dense breast tissue for two reasons: having dense breasts inherently increases your risk for breast cancer by two to four times, and the denser your breasts are, the harder it is for radiologists to spot cancer. The denser your breasts are, the whiter they look on imaging; cancer also looks white. So white on white makes it hard for me to see through that dense breast tissue to find the cancer.

Why is having dense breasts such a hot topic?

We've always known about dense breast tissue, but we never realized its true implications as a cancer risk factor. Now, federal notification laws are sweeping the nation. In Illinois, not only is it required to inform patients they have dense breasts, but insurance companies are required to cover a supplemental screening exam to help screen for women with dense breast tissue.

Can a woman figure out on her own if she has dense breasts – are they the same as firm breasts?

No, and you can't tell just by feeling. The biggest factors are age and genes: younger females with estrogen in their body traditionally have denser breast tissue, while if your mom had dense breast tissue, you're more likely to have it. Dense breasts have nothing to do with body weight or body build. You can be a bigger woman with dense breasts or a smaller woman with fatty breast tissue. After menopause, a women's breast density usually decreases as their estrogen decreases, unless they are taking hormone replacement therapy.

How do dense breasts affect self-exams?

It doesn't really matter if you have dense breast tissue or not. But let's back up about breast self-exams: they're falling out of vogue and are no longer included in the USPSTF guidelines. What matters is getting comfortable with what your breasts feel like. No breast feels the same, it's like a fingerprint. 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.

If a woman has dense breasts, what are her options for breast cancer screening?

The first option is 3D mammography, or tomosynthesis. This imaging creates one millimeter 'slices,' of your breasts, meaning the radiologist has 90 to 100 images to scroll through and scrutinize for cancer through that dense breast tissue. The second option is whole breast ultrasound; for this, you lay comfortably on a bed, gel is put on you and a probe is gently moved across each breast for 5 to 10 minutes. The last test is an MRI. For this, you lie on your belly and your breasts hang through circular coils that help pick up the magnetic signal that's being elicited through your breast tissue to show images on an MRI.

What are some of the more talked about drawbacks to these different tests?

Many women fear how tight their breasts will be squeezed in a mammogram. When we compress the breast, we're reducing its thickness -; and the amount of radiation needed to get a good picture. Now, new technology called smart curve paddles hug your breast instead of mashing it into a pancake. The other concern being mentioned is gadolinium, the contrast we inject in patients for MRIs. Last year, the FDA discovered patients were retaining gadolinium in their bodies. There are now newer contrast agents coming out; we're the lead test site for gadopiclenol, which is in phase III clinical trials and is supposed to have no retention and deposition. So I think these fears are no longer necessary.

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

In the 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 best. 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 add a whole breast ultrasound or breast MRI to your regimen. The key is to understand your risks and know that there are tools out there to help you.