FDA's Updated Mammogram Regulations Aim to Protect People With Dense Breasts

Mammogram providers will be required to notify patients if they have dense breasts, and explain how dense breasts may influence the accuracy of mammography, the Food and Drug Administration said in a news release on Thursday.

The updated regulations are meant to improve patient access to information about what it means to have dense breasts, how dense breasts may influence breast cancer risk, and how best to create a comprehensive breast health strategy with their healthcare provider.

"Today’s action represents the agency’s broader commitment to support innovation to prevent, detect, and treat cancer,” Hilary Marston, MD, MPH, the FDA's chief medical officer said in the news release.

Approximately 50% of all women 40 and older who get mammograms have dense breasts, which is considered a risk factor for breast cancer. Additionally, dense breasts may make mammograms harder to read and interpret, ultimately making mammography less sensitive, or more likely to miss cancer.

The updated regulations are required to roll out within the next 18 months, nationwide. Here's how the FDA's new guidance may affect your next mammogram.

What Does It Mean to Have Dense Breasts?

All breasts contain a combination of glandular tissue, fibrous connective tissue, and fatty breast tissue. Breast density refers to the amounts of certain types of breast tissue in relation to other types.

Specifically, dense breasts have larger amounts of glandular tissue and fibrous connective tissue, compared to fatty tissue.

A person's breast density can be identified on a mammogram—in fact, a system called the Breast Imaging Reporting and Data System (BI-RADS), developed by the American College of Radiology, classifies breast density into four categories:

• Entirely fatty breast tissue: Breasts have almost all fatty tissue.
• Scattered fibroglandular breast tissue: Breasts have mostly fatty tissue with some areas of dense glandular and fibrous connective tissue.
• Heterogeneously dense breast tissue: Breasts have many areas of dense glandular and fibrous connective tissue, with some areas of fatty tissue.
• Extremely dense breast tissue: Breasts have almost all dense glandular and fibrous connective tissue.

Most women fall into the two middle categories. Scattered fibroglandular breast tissue and heterogeneously dense breast tissue are found in 80% of women—each category is found in 40% of women. About 10% of women have entirely fatty breast tissue, and about 10% have extremely dense breast tissue.

How Will Breast Density Be Shared With Patients?

Prior to the updated regulations, mammogram providers weren't required to include breast density in reports given to healthcare providers, or provide a lay summary to patients with dense breasts.

That said, between 2009 and 2021, 38 states passed laws mandating the notification of breast density, though requirements do vary from state to state.

That means some people who get mammograms may not notice any changes in their healthcare, said Sandra B. Brennan, MBBCh, BAO, FRCR, director of radiology at Memorial Sloan Kettering Westchester. "But for women in states without breast density legislation...these women will [now] be informed of their breast density."

Nationwide, breast density will be classified into one of the following categories, with the following language:

• A: "The breasts are almost entirely fatty."
• B: "There are scattered areas of fibroglandular density."
• C: "The breasts are heterogeneously dense, which may obscure small masses."
• D: "The breasts are extremely dense, which lowers the sensitivity of mammography."

Breasts are considered "not dense" if they fall into categories A or B. In that case, the FDA instructs that the summary given to the patient should include this statement:

If an individual's mammogram results fall into category C or D, their breasts are considered to be dense. That patient's summary should include the following language:

Breast density results are required to be shared with patients within 30 days of the mammogram—that number goes down to just seven days if a person's mammogram shows imaging that may suggest breast cancer.

Risks Associated With Dense Breasts

Having dense breasts can influence a person's breast cancer risk and impact a breast cancer diagnosis.

"In breasts that are dense, cancer may be difficult to see on a mammogram," Brennan explained. "Dense tissue appears white on a mammogram and may obscure a cancer."

People with dense breasts also have a higher risk of developing breast cancer. Compared to people with fatty breasts, people with dense breasts are four to five times more likely to develop breast cancer, though it's not entirely clear why.

Because of this increased risk, notifying people of their breast density can help them make more informed decisions about their health. The updated FDA regulations recommend patients with dense breasts talk to their healthcare provider; that conversation may include information on additional imaging tests.

At this time, there are no specific additional screening recommendations for people with dense tissue, said Laura Dean, MD, a breast radiologist at the Cleveland Clinic. But they may benefit from a variety of additional screenings, in tandem with their mammogram.

"Women with dense breasts can consider supplemental imaging tests such as ultrasound, contrast-enhanced mammography, or MRI [magnetic resonance imaging]," Brennan noted, adding that, depending on an individual's risk profile and unique situation, one type of imaging test may be preferred over the other, and should be discussed with a healthcare provider.

In any case, according to Dr. Dean, "the goal of screening is to detect breast cancer as early as possible, when cancers are smaller, lower stage, and easier to treat."

Though additional imaging may be able to detect harder-to-find breast cancer in some people, it may come with extra risks. "Supplemental imaging tests can increase cancer detection, but may lead to additional tests of even benign biopsies," said Brennan.

Supplemental cancer screenings may also come with additional costs—while mammograms are free for the majority of people with breasts, health insurers may not cover extra tests.

However, a bill in the U.S. House of Representatives—the Find It Early Act—aims to level the cost playing field for additional breast cancer screenings. The legislation would ensure all health insurance plans cover screenings, diagnostic mammograms, breast ultrasounds, and MRIs for people with dense breasts or at a higher risk of breast cancer with no out-of-pocket costs.

As for the updated FDA regulations, experts hope that this will only "strengthen the fight against breast cancer," Brennan said. "By empowering patients with more information, they can make informed decisions regarding their breast healthcare."