Even in states that require notification of dense breasts after mammography or insurance coverage for additional screening, ultrasound and magnetic reconnaissance imaging rates remain low, according to a recent study in JAMA Network Open.

Laws mandating insurance companies cover recommended additional screening vary by state but national legislation requiring notification of dense breasts after mammography took effect in 2024.

“Obviously, having legislation and access hardcoded in is good, but it doesn’t necessarily guarantee that everybody gets” the necessary supplemental screening, said VK Gadi, MD, PhD, deputy director of the University of Illinois Cancer Center in Chicago, and a medical oncologist at UI Health in Chicago, who was not involved in the research. “It’s not happening at the rate it should.”

About 1 in 8 women in the US develop breast cancer. Guidelines on when additional screening for dense breasts vary across organizations. The American College of Physicians recommends supplemental digital breast tomosynthesis for asymptomatic women with heterogeneously or extremely dense tissue. The group recommends against using MRI or ultrasound, while the US Preventive Services Task Force cites insufficient evidence to recommend for or against either imaging.

Almost half of the women aged 40 years or older have dense breasts. Dense tissue cannot be felt during a clinical exam; only a radiologist can make the determination.

Researchers analyzed national insurance claim data over a 10-year period starting in 2008, of more than 12 million women between ages 40 and 64 (mean age, 51.3 years) who received routine mammography to determine rates of supplemental ultrasonography or MRI within 6 months of initial screening. They did not have data on breast density and were not able to compare rates between those with dense tissue and those without.

A little over 20% of the women lived in a state with notification laws, the majority of which also mandated information about supplemental screening.

Overall, rates of additional imaging were low with 9% receiving ultrasound and.6% receiving MRI. In states that adopted a notification law during the study period, a nearly 3 percentage-point increase in ultrasound was observed in a weighted model within 15 months of the legislation change.

Notification mandates were associated with slightly higher use of ultrasonography (adjusted odds ratio [aOR], 1.09; 95% CI, 1.08-1.10) and MRI (OR, 1.09; 95% CI, 1.06-1.12) than in states without the laws after adjustment for states and time. Congressional legislation requiring notification of dense breasts after mammography took effect in 2024.

Just over 7% and 3% of women lived in a state with laws mandating ultrasound or MRI insurance coverage, respectively. Living in these states was associated with 88% higher odds of receiving ultrasound (1.86-1.9) but not MRI (aOR, 1.01; CI,.96-1.05).

Yamilé Molina, MPH, PhD, associate director for community outreach and engagement at the University of Illinois Cancer Center in Chicago, said patients, including those in historically underserved populations, are becoming more informed about the risks associated with having dense breasts.

“There is growing awareness and they have proactive questions,” she said. “And what we really want is [for clinicians] to validate patients’ questions around [breast density] vs saying, ‘Well, we’ll have to just wait till the results.’”

No matter where a clinician practices, the best way to increase rates of screening is to have conversations with patients to help them understand what it means to have dense breasts and emphasize the importance and availability of additional screenings, said Chan Shen, PhD, a researcher at the Penn State Cancer Institute in Hershey, Pennsylvania, who led the study.

“Notification sort of opens the door, but then it’s not the end of the pathway. Patients need clinicians to give them more information,” Shen said.

Ultrasound and MRI are also not the only options available for additional imaging. Three-dimensional (3D) mammography was introduced over a decade ago and “is much, much better” with showing masses in dense breast tissue, Gadi said. Many practices exclusively use this technology.

“The data and the legislation lag behind what we’re seeing with the technology,” since some states have passed new laws requiring insurance to cover 3D mammograms, he said.

This study was funded by the Pennsylvania Breast Cancer Coalition. Gadi reported receiving consulting fees from Hologenic, which develops medical imaging technology. Shen and Molina reported having no financial disclosures.

Kelsey Mesmer, PhD, is a freelance journalist and journalism professor at Saint Louis University in St. Louis.