Racial Differences in Screening Eligibility by Breast Density After State-Level Insurance Expansion.

Importance: Women with dense breasts have elevated risk of false-negative mammograms and may benefit from supplemental screening. Objective: To assess potential outcomes of Pennsylvania's law mandating insurance coverage for supplemental breast cancer screening among Black and White women. Design, Setting, and Participants: This cross-sectional study included Black and White women, aged 40 to 74 years, without prior breast cancer or known BRCA1/2 variants who underwent mammography screening at a large urban academic health system from January 2015 to December 2021, with cancer outcomes ascertained through December 2022. Data analysis was conducted from June 2023 to April 2025. Exposures: Dense breasts; the law mandates insurance coverage for women with extremely dense breasts or those with heterogeneously dense breasts plus a greater than 20% lifetime breast cancer risk by risk models. Main Outcomes and Measures: The main outcomes were odds of eligibility for supplemental coverage and of a false-negative mammogram. Results: A total of 68 478 women (38 397 Black women [median (IQR) age, 57 (49-64) years] and 30 081 White women [median (IQR) age, 58 (49-65) years]) were used for the analysis. Fewer Black women had extremely dense breasts (561 [2.1%] vs 1464 [5.8%]; P = .02) and greater than 20% lifetime risk of breast cancer identified (257 [0.7%] vs 1905 [6.4%]; P = .04) compared with White women. Consequently, Black women were less likely to meet the eligibility criteria for supplemental screening (523 [1.6%] vs 2081 [8.4%]; P = .02). The criteria showed lower sensitivity but higher specificity for detecting false-negative mammograms in Black compared with White women in one round of screening. Using heterogeneously or extremely dense breasts alone would detect more false negatives but with significantly more women recommended for magnetic resonance imaging. Conclusions and Relevance: In this study of 68 478 screening mammograms among Black and White women from 2015 to 2021, retrospectively applying criteria for supplemental screening based on heterogeneously or extremely dense breast density and lifetime risk had limited ability to identify women at risk for a false-negative mammogram. Given lower density and lifetime risk estimates, few Black women met criteria for insurance coverage in Pennsylvania, and the criteria had poor sensitivity for identifying Black women with false-negative mammograms. Additionally, using the current breast density criteria for magnetic resonance imaging may not accurately reflect breast cancer risk in Black women.