Background

Lung cancer is the leading cause of cancer-related mortality in the United States, with outcomes disproportionately worse among uninsured and socioeconomically disadvantaged populations. The Affordable Care Act (ACA), through Medicaid expansion, sought to improve access to care, yet its long-term impact on lung cancer survival remains incompletely defined.

Objective

To evaluate the association between Medicaid expansion and overall mortality in patients with lung cancer, and to determine whether effects varied by stage at diagnosis, race/ethnicity, socioeconomic status, and treatment modality.

Methods

We conducted a retrospective cohort study using the National Cancer Database, including patients aged 40–64 years diagnosed with lung cancer between 2006 and 2021. States were categorized as early Medicaid expansion (by January 2014) or non-expansion. The study period was divided into pre-expansion (2006–2013) and post-expansion (2014–2021). A Difference-in-Differences (DiD) analytic approach within a Cox proportional hazards framework was used to estimate the effect of Medicaid expansion on all-cause mortality, adjusting for demographic, clinical, and socioeconomic factors.

Results

The study cohort comprised 369,251 patients, predominantly White (74.7%) and male (52.7%), with a mean age of 56.8 ± 5.6 years. A total of 165,364 individuals (44.8%) resided in early Medicaid expansion states. Medicaid expansion was associated with a 45.2% reduction in overall mortality. Stratified analyses demonstrated reductions in the hazard of overall mortality across all racial and ethnic groups, with the greatest benefit observed among Hispanic patients (DID: –0.506; 95% CI, –0.729 to –0.283; p < 0.001). Expansion states also showed increased early-stage diagnoses, reduced uninsured rates, and higher surgical utilization following the ACA.

Conclusions

Medicaid expansion was significantly associated with improved lung cancer survival across demographic and clinical subgroups. These findings underscore the role of insurance policy in shaping oncologic outcomes and suggest that Medicaid expansion may serve as a critical strategy to enhance access to timely diagnosis and treatment.