Abstract
IMPORTANCE: Medicaid expansion under the Affordable Care Act broadened eligibility for government-funded health coverage. This may have improved access to early diagnosis and rapid treatment, potentially impacting survival in patients with resectable non-small cell lung cancer (NSCLC), a leading cause of cancer-related death in the US. OBJECTIVE: To evaluate the association between state-level Medicaid expansion and all-cause mortality in patients with resectable NSCLC. DESIGN, SETTING, AND PARTICIPANTS: This cohort study of patients aged 20 to 64 years who were diagnosed with stage I to IIIA NSCLC used data from the Surveillance, Epidemiology, and End Results registry collected between January 1, 2006, to December 31, 2019, with outcomes administratively censored at 2 and 4 years. Data were analyzed between March 1 and September 10, 2025. EXPOSURE: Medicaid expansion status of patients' state of residence at diagnosis. Patients' states of residence were categorized as nonexpansion, early expansion (2011), 2014 expansion, or late expansion (after 2014). MAIN OUTCOMES AND MEASURES: Primary outcomes were 2- and 4-year all-cause mortality. Cox proportional hazards regression models within a difference-in-differences framework were used to estimate adjusted hazard ratios (HRs) for death. Secondary analyses evaluated postexpansion mortality trends and changes in early-stage (I-II) diagnoses using logistic regression. RESULTS: Among 53 842 patients included in the analysis (24 849 [46.2%] 60-64 years of age; 27 027 [50.2%] male), propensity score-matched analyses showed lower 2-year mortality in states with early expansion (HR, 0.95; 95% CI, 0.91-0.99; P = .02) and 2014 expansion (HR, 0.91; 95% CI, 0.86-0.95; P < .001) compared with nonexpansion control states, whereas no significant difference was observed in late expansion states (HR, 0.95; 95% CI, 0.89-1.02; P = .15). All expansion groups showed decreased mortality. Mortality decreases were observed after the first 3 years and persisted throughout the study period. The proportion of early-stage diagnoses did not change post expansion, suggesting benefits may have been mediated by improved postdiagnostic care rather than earlier detection. CONCLUSIONS AND RELEVANCE: In this cohort study of patients with stage I to IIIA NSCLC, Medicaid expansion was associated with lower mortality at 2 and 4 years. These findings suggest that expanded insurance coverage may have enhanced access to effective cancer care and improved population-level outcomes.