Looking Beyond Breast Density: MRI Biomarker May Refine Breast Cancer Risk Assessment
Background parenchymal enhancement findings raise new questions about risk and access
Breast density has become a cornerstone of breast cancer risk assessment and decisions about supplemental MRI screening. But new research suggests another MRI finding—background parenchymal enhancement (BPE)—may reveal important risk information that density alone misses, particularly for Black women.
“Black women in the U.S. have 40% higher breast cancer mortality compared to white women,” said Anne Marie McCarthy, ScM, PhD, associate professor of epidemiology at the University of Pennsylvania Perelman School of Medicine in Philadelphia. “This disparity has been very persistent over the past several decades.”
Dr. McCarthy coauthored a Radiology study finding that Black women were more likely than white women to exhibit high BPE on breast MRI, even though they were less likely to have extremely dense breasts.
“Black women are also more likely to be diagnosed at later stages of disease, yet existing breast cancer risk models identify relatively few Black women as high risk,” Dr. McCarthy said. “We need to better understand breast cancer risk among Black women and identify risk factors that are relevant to this population.”
Current screening frameworks rely heavily on mammographic breast density. Women with dense breasts face both increased cancer risk and reduced mammographic sensitivity, making density an important factor in determining eligibility for supplemental MRI screening.
But density may not capture the full picture.
“Breast density reflects the amount of fibroglandular tissue relative to fat on mammography, whereas BPE reflects the degree of enhancement of normal breast tissue on contrast-enhanced MRI, which we believe corresponds more closely to hormonally active tissue,” Dr. McCarthy said. “Importantly, BPE and density are related but distinct. Higher BPE has been shown to be associated with increased breast cancer risk independent of breast density.”
Radiologists categorize BPE on breast MRI using BI-RADS terminology as minimal, mild, moderate or marked.
The retrospective study included 2,489 women without a history of breast cancer who underwent both mammography and breast MRI between 2016 and 2023. The cohort included 388 Black women and 2,101 white women.
Researchers found that Black women were less likely than white women to have extremely dense breasts (11% vs. 21%). Unadjusted rates of high BPE, defined by the team as moderate or marked enhancement, were similar between groups.
However, after adjusting for age, menopausal status, body mass index and breast density, Black women had 31% higher odds of exhibiting high BPE than white women. “When we held these factors constant, we saw Black women had higher levels of BPE,” Dr. McCarthy said.
One possible explanation for the disconnect between lower density and higher adjusted BPE in Black women noted by Dr. McCarthy is that the two biomarkers measure different underlying processes. “One hypothesis is that BPE captures hormonal or metabolic factors—such as estrogen exposure—that are not well represented by density,” she said.
She cautioned that the findings should be interpreted carefully because the study population was relatively small and limited to women who underwent MRI. “But it is intriguing and might point to real differences in breast tissue that could have implications for breast cancer risk,” Dr. McCarthy said.
Michael H. Fuchsjäger, MD, professor and chairman of radiology, and Gabriel Adelsmayr, MD, PhD, a consultant radiologist, both from the Department of Radiology at the Medical University of Graz in Austria, coauthored an editorial related to the study.
“The most important message is that a density-centered paradigm in breast cancer risk assessment is powerful but likely incomplete,” Dr. Fuchsjäger said. “BPE is not just an imaging feature, but potentially a risk marker. It reflects a more dynamic, hormone-driven environment, whereas breast density is primarily structural.”
Balancing BPE’s Promise with MRI Access Gaps
Drs. McCarthy and Fuchsjäger both emphasized that enthusiasm surrounding BPE must be balanced with caution, particularly because breast MRI access already remains uneven across patient populations.
“What concerns us is that breast MRI is already unevenly distributed by scanner availability, workforce, payer policy and referral patterns,” Dr. Fuchsjäger said. “There is a real risk that the population who should benefit most—Black women with low mammographic density but potentially higher BPE—is precisely the population least likely to be reached, simply because they’re less likely to be referred for MRI to begin with.”
Dr. McCarthy noted that MRI screening is currently recommended primarily for women with pathogenic mutations or very high lifetime breast cancer risk.
“If BPE proves to be a reliable and reproducible marker of risk across diverse populations, it could help refine individualized risk assessment, especially for women whose risk is not fully captured by family history or breast density alone,” she said.
Before BPE can be incorporated into clinical guidelines or formal risk models, the researchers say it will need to be further validated.
“We need larger prospective studies in diverse populations to assess BPE and its association with breast cancer risk,” Dr. McCarthy said. “I’m also interested to see how BPE correlates with different tumor characteristics.”
For now, Dr. Fuchsjäger said radiologists should continue reporting BPE consistently while recognizing that evidence-based management recommendations are still evolving. “BPE should be recognized as risk-relevant, but caution is needed before escalating surveillance based on BPE alone,” he said.
Dr. McCarthy said the study represents an important early step toward understanding how imaging biomarkers may intersect with equity in breast cancer care. “Our findings suggest that BPE may help reveal important differences in breast tissue biology and risk that are particularly relevant for Black women,” she said.
“Race in our analysis reflects social and structural contexts rather than biology, and future work must better disentangle these influences,” Dr. McCarthy added. “If we are serious about equity in breast imaging, we must ensure that emerging risk markers are studied in diverse populations from the outset.”
For More Information
Access the Radiology study, “Black-White Racial Differences in Background Parenchymal Enhancement at Breast MRI,” and the related editorial, “Background Parenchymal Enhancement and Race: An Emerging MRI Breast Cancer Risk Predictor.”
Read previous RSNA News stories on breast imaging: