Insurance requirements for supplemental breast imaging are far more effective at increasing screening access than simply notifying women they have dense breast tissue. A large nationwide study found that when states mandate insurance coverage for ultrasounds and MRIs after mammograms, supplemental imaging use jumps dramatically compared to notification-only laws. More than 40% of American women age 40 and older have dense breast tissue, which can make cancer harder to detect on standard mammograms and is associated with higher cancer risk.

What Is Dense Breast Tissue and Why Does It Matter?

Breasts are made up of three types of tissue: fibrous connective tissue, glandular tissue, and fatty breast tissue. When someone has dense breasts, they have more fibrous and glandular tissue, which appears white on a mammogram, similar to how abnormal changes like tumors appear. This creates a visibility problem: dense tissue can mask cancer on standard imaging, making it harder for radiologists to spot problems. Unlike other breast characteristics, dense tissue cannot be felt during a physical exam and can only be detected through medical imaging.

Because of this challenge, several states have passed legislation to increase awareness of breast density and improve access to supplemental screening options like ultrasound and MRI scans.

How Do Breast Density Laws Actually Work?

Researchers from Penn State College of Medicine analyzed health records from 12.6 million American women between ages 40 and 64 to understand how different types of legislation affect screening behavior. They examined data from women who received routine mammograms between 2008 and 2019 and found two main categories of state laws:

• Notification Laws: These require medical facilities to inform women when dense breast tissue is found on a mammogram. About 21% of women in the study lived in states with notification laws, and nearly 60% of those states required the notification to include information about supplemental screening options.
• Insurance Coverage Mandates: These require health insurance companies to cover the cost of follow-up imaging tests. Only 7% of women in the study lived in states requiring ultrasound coverage, and 3% lived in states requiring MRI coverage.

What Did the Research Actually Show?

The findings were striking. Insurance coverage mandates had nearly four times the impact of notification laws alone. When states required insurance companies to cover supplemental ultrasounds, use increased by roughly 47 additional ultrasounds per 1,000 women screened. In contrast, notification laws were associated with only about 13 additional ultrasounds per 1,000 women screened.

For MRI imaging, the pattern was different. Notification laws were associated with a small increase, about one additional MRI examination per 1,000 women screened. However, insurance coverage mandates for MRIs did not produce a statistically significant change in MRI use. Researchers believe this is because people with a personal or family history of breast cancer are already much more likely to seek MRI imaging, making legislative efforts less impactful for this particular test.

"Notification opens the door for patients to discuss breast density and supplemental screening with their healthcare provider, but it's not enough if we're trying to lower barriers for patients," said Chan Shen, Howard E. Morgan Professor in Surgery and professor of public health sciences at Penn State College of Medicine.

Chan Shen, Howard E. Morgan Professor in Surgery and Professor of Public Health Sciences, Penn State College of Medicine

Why Is Cost Such a Powerful Factor?

The dramatic difference between notification and insurance coverage laws highlights a critical barrier to screening: cost. Even when women are informed they have dense breasts and told that supplemental screening might be appropriate, many do not pursue follow-up imaging if they must pay out of pocket. Removing that financial barrier through insurance mandates makes screening far more accessible.

MRI imaging presents additional challenges beyond cost. MRIs are generally more expensive tests than ultrasounds, and fewer medical facilities offer them. These logistical barriers may prevent women from seeking this type of imaging even when insurance covers it.

Who Is Most Likely to Miss Out on Supplemental Screening?

Despite the increases driven by legislation, overall supplemental imaging use remains surprisingly low. Across the entire study sample, only 9% of women received supplemental ultrasound imaging within six months of a screening mammogram, and just 0.6% received supplemental MRI. This is striking given that more than 40% of middle-aged and older women have dense breasts.

Certain groups were even less likely to get follow-up screening:

• Age: Older women were less likely to receive supplemental imaging after mammography.
• Geography: Women living in rural communities had lower rates of follow-up screening, likely due to limited access to imaging facilities.
• Health Status: Women with other health conditions were less likely to pursue supplemental screening.

How to Advocate for Better Breast Screening Access

If you have dense breast tissue, there are steps you can take to ensure you receive appropriate screening:

• Ask About Your Breast Density: Request that your healthcare provider inform you of your breast density status after your mammogram. This information should be included in your screening results.
• Discuss Supplemental Screening Options: Talk with your doctor about whether supplemental ultrasound or MRI screening is appropriate for you based on your individual risk factors and breast density.
• Understand Your Insurance Coverage: Check with your insurance company to learn what supplemental imaging tests are covered in your state. If coverage is limited, ask your healthcare provider about payment options or facilities that offer reduced-cost screening.
• Know Your State's Laws: Research whether your state has notification laws, insurance coverage mandates, or both. This information can help you understand what screening options should be available to you.

What Do Experts Say About the Path Forward?

On the federal level, the Food and Drug Administration began requiring mammography facilities to inform people whether they have dense breasts in 2024. However, there are currently no federal laws mandating insurance coverage for supplemental testing. This means that access to follow-up imaging varies significantly depending on where you live.

"Not everyone with dense breasts needs supplemental screening, but you first need to be aware whether or not you have dense breasts to make that decision in consultation with your healthcare provider," said Chan Shen.

Chan Shen, Howard E. Morgan Professor in Surgery and Professor of Public Health Sciences, Penn State College of Medicine

The research suggests that while notification laws are a necessary first step, they are insufficient on their own. To truly maximize the public health impact of dense breast legislation, policymakers should prioritize insurance coverage mandates that remove financial barriers to supplemental screening. At the same time, addressing logistical and geographical barriers remains critical to ensure that all women, regardless of where they live or their economic circumstances, have equal access to appropriate breast cancer screening.