Black-White Racial Differences in Background Parenchymal Enhancement at Breast MRI

Background Women with high background parenchymal enhancement (BPE) at contrast-enhanced MRI have up to a fourfold increased risk of breast cancer, even after adjusting for breast density. However, no studies have examined BPE specifically among Black women, despite their higher breast cancer-specific mortality and typically lower breast density. Purpose To examine Black-White racial differences in contrast-enhanced MRI-derived BPE. Materials and Methods This retrospective cross-sectional study examined the data of Black and White women without a history of breast cancer who underwent both mammography and subsequent MRI as part of a screening or diagnostic workup between January 2016 and December 2023. BPE was assessed qualitatively according to the Breast Imaging Reporting and Data System as high (ie, moderate or marked) or low (ie, minimal or mild). Logistic regression was performed to assess the association between race and high BPE, and mediation analysis was performed to explore the extent to which density accounted for racial differences in BPE. Results A total of 388 Black women and 2101 White women were included, with mean ages of 47 years ± 10 [SD] and 48 years ± 11, respectively. Fewer Black women had extremely dense breasts at mammography (43 of 388 [11%] vs 435 of 2101 [21%]; P = .01). The proportions of both groups exhibiting high BPE at breast MRI were similar (38% vs 33%; P = .11). According to mediation analysis, Black women were 31% more likely to have high BPE levels after density differences were eliminated (odds ratio, 1.28; 95% CI: 1.01, 1.64; P = .03). Conclusion In this preliminary examination of BPE as a breast MRI marker for the risk of invasive breast cancer, Black women were more likely than White women to have high BPE, despite the latter typically having greater breast density.