Long-term Effect of the Medicaid Expansion Program on Cancer Mortality by U.S. Region, Gender and Race/Ethnicity

BACKGROUND: Cancer remains the second leading cause of death in the United States, with persistent racial/ethnic and socioeconomic disparities. Expanding healthcare access is a key strategy for addressing these inequities. We considered Medicaid expansion as a natural experiment to assess whether broader access is associated with changes in cancer mortality overall and by U.S. region, gender, and race/ethnicity. METHODS: Using 2005-2019 state-level data from the U.S. Census, CDC WONDER, Kaiser Family Foundation, and America's Health Rankings, we compared age-adjusted cancer mortality (per 100,000 adults aged 25-64) between 27 expansion and 24 non-expansion states. We applied a person-time weighted generalized synthetic control method, adjusting for demographic, socioeconomic, and healthcare access variables. This improves robustness to violations of the parallel trends assumption that may have limited prior analyses. RESULTS: Expansion was associated with an overall reduction in cancer mortality (mean difference [MD]: -2.06; 95% CI: -4.24 to 0.11). Subgroup analyses revealed reductions in cancer mortality among women (MD: -3.02; 95% CI: -5.28 to -0.77), non-Hispanic Whites (MD: -2.27; 95% CI: -4.15 to -0.38), and Northeastern states (MD: -4.46; 95% CI: -7.40 to -0.89). CONCLUSIONS: Findings suggest Medicaid expansion had a heterogeneous impact on cancer mortality. While reductions were evident overall, particularly among White individuals, women, and those in the Northeast, imprecise estimates limited evidence of benefit for racial/ethnic minorities, men, and other regions, where disparities are more pronounced. This may also reflect inequities in healthcare access, quality, utilization, and risk factor distribution (e.g., smoking). Future research should assess long-term impacts across broader outcomes and populations.