Mammogram results must let women know about their breast density, FDA mandates

All women who undergo breast cancer screening with a mammogram in the U.S. will find out if they have dense breasts — a risk factor for developing breast cancer.

On March 9, 2023, the U.S. Food and Drug Administration published updates to mammography regulations to require that clinics notify patients about the density of their breasts.

The information will also explain how breast density can influence the accuracy of mammography and recommend patients with dense breasts talk to their doctor about what it means and how it relates to their breast cancer risk.

The updated regulations must be implemented within 18 months, according to the FDA.

Many women already receive this notification because 38 states have breast density reporting laws, according to, a nonprofit dedicated to the topic. That's thanks to grassroots efforts by patients who felt blindsided because they weren’t told their mammograms could be more difficult to interpret due to their dense breasts.

A recent study found most women may be unaware having dense breasts increases their risk of developing breast cancer.

The research, published Jan. 23 in the journal JAMA Network Open, looked at surveys and interviews with more than 2,300 women.

The study found that women believe a family history is the strongest risk factor for breast cancer, and few participants knew that having dense breasts increases the risk of developing breast cancer. Dense breasts increase one's risk of breast cancer by one to four times, according to the study; a close family member with breast cancer increases risk by about three times, according to the American Cancer Society.

Many women surveyed also said they didn't think they could reduce their risk of developing breast cancer, leading the researchers to conclude that "comprehensive education about breast cancer risks and prevention strategies is needed," they wrote in the study.

Related: After Katie Couric was diagnosed with breast cancer, she chose a lumpectomy, not a mastectomy, as her treatment. What to know about breast-conserving surgery.

What does it mean if a patient has dense breasts? asked Dr. Deanna Attai, past president of the American Society of Breast Surgeons and an associate clinical professor of surgery at the David Geffen School of Medicine at the University of California Los Angeles; and Dr. Dana Smetherman, past chair of the American College of Radiology Breast Imaging Commission and chair of radiology at Ochsner Medical Center in New Orleans.

What does it mean if a woman has dense breasts?

It has to do with the proportion of fatty tissue, glandular tissue and fibrous connective tissue in the breast. The more fibro-glandular tissue a woman has, the denser the breast.

Age is the biggest factor: Younger women naturally tend to have denser breast tissue. As estrogen levels drop with menopause, much of that glandular tissue gets replaced by fatty tissue.

Thinner women often have dense breast tissue. For others, it’s hereditary or just how they’re born. More than half of women over 40 in the U.S. have dense breasts, which is a risk factor for developing breast cancer, the FDA noted.

Having dense breasts is not something a person can see or feel — it’s different from having a lumpy breast, Attai said — rather, it’s determined by a mammogram.

Related: Lumps and bumps are often early signs of breast cancer. These pictures of breast cancer bumps show you what to look for to determine if it's a cause for concern.

How do dense breasts affect mammogram readings?

Dense tissue shows up as white on X-rays — think of how bones stand out in those images.

“When I as a breast imaging radiologist describe a patient as having dense breasts, what I mean is that her mammogram looks white to me,” Smetherman said. “Cancers will also look white, so looking for something white on a background of white is more difficult to identify.”

Fatty tissue, on the other hand, looks gray on a mammogram, so a tumor stands out.

Should women with dense breasts still have a mammogram?

Absolutely, both experts emphasized. “That’s a very, very important message,” Smetherman noted. Women will still benefit from mammography, which is the only FDA-approved screening tool for breast cancer.

Mammograms are sometimes the only way to detect calcifications, which are associated with early stages of breast cancer in some cases, Attai said.


What are the next steps for women with dense breasts?

A 3D mammogram can improve the cancer detection rate, Attai said. It’s not always covered by insurance.

A breast ultrasound or a breast MRI can be helpful as supplemental screenings, but those tests are not automatically recommended. They may find more suspicious spots — which may lead to biopsies and other invasive procedures — but there hasn’t been much data to show they improve survival.

“The harder we look, the more we’re going to find. Not everything we find needs to be found. With all of these tests, there are false alarms, false positives,” Attai said. “There’s a lot of nuance to this — it’s not quite black and white.”

“It’s one reason why we have to be very cautious before you say, ‘Yes, everybody with dense breasts should have this additional thing’,” Smetherman added.

Right now, women who have dense breasts and who are considered to have a high lifetime risk of developing breast cancer — perhaps because of family history or other factors — get a routine annual MRI, Attai said.

Does the FDA rule mean insurance will cover the cost of additional screening for women with dense breasts?

No, at least not yet. The change will “enhance the communication of important clinical information” between patients, doctors and mammogram centers, but the FDA doesn’t regulate insurance coverage, said Megan McSeveney, a spokeswoman for the agency.

Some states require insurance to cover supplemental screening beyond mammography, according to The majority don't.

The typical out-of-pocket cost for a breast screening ultrasound is about $250, according to the Brem Foundation to Defeat Breast Cancer. The average cost of an MRI is about $1,084, it noted.

When Attai recommends supplemental screening for women who have a high risk of developing breast cancer, she usually has no problems getting their insurance to cover those tests. For all other women, it’s all across the board. The FDA rule could be a first step in changing that, she said.

“It’s going to take a lot to change insurance companies,” Attai noted. “(But) coming from a federal level, that may ... help influence insurance companies to cover supplemental screening or at least 3D mammography.”

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