Early- and Late-Stage Cancer Diagnosis Under 3 Years of Medicaid Expansion.

Introduction: Health insurance expansions may increase early detection of cancer and reduce late-stage cancer incidence. The study assesses the effects of the Affordable Care Act Medicaid expansions on rates of early- and late-stage cancer diagnosis up to 3 years after implementation.

Methods: Population-based quasi-experimental analysis of nonelderly adults was conducted in 732 counties from the 2010-2016 Surveillance, Epidemiology, and End Results Program cancer registry data. Multivariate event study regressions were estimated to compare annual changes in county-level rates of cancer diagnoses in states that expanded Medicaid with those that did not. Data analysis was performed from May to October 2019.

Results: Medicaid expansion was associated with an increase in early-stage cancer diagnoses of 21.3 per 100,000 population (95% CI=2.9, 35.2) or 9.14% of population in its first year; estimates for Years 2 and 3 were also positive but smaller and not statistically significant. There was a marginally significant reduction in late-stage diagnoses of 8.7 per 100,000 population (95% CI= -25.0, 3.4) or 5.7% of population relative to baseline, 3 years after Medicaid expansion. There was no detectable effect of expansion on total diagnoses.

Conclusions: Medicaid expansions increased early-stage cancer diagnosis in the first year of expansion, but effects dissipated in subsequent years, suggesting a response to pent-up patient demand for screening and diagnostic services immediately after expansion. There was also suggestive evidence of reductions in late-stage diagnosis in the third year of Medicaid expansion, highlighting the potential role of public health insurance in improving cancer outcomes among nonelderly adults.