PURPOSE: To examine the association between historic state Medicaid income eligibility limits and long-term survival among patients with cancer. METHODS: 1,449,144 adults age 18-64 years newly diagnosed with 19 common cancers between 2010 and 2013 were identified from the National Cancer Database. States' Medicaid income eligibility limits were categorized as ≤ 50%, 51%-137%, and ≥ 138% of federal poverty level (FPL). Survival time was measured from diagnosis date through December 31, 2017, for up to an 8-year follow-up. Multivariable Cox proportional hazards models with age as time scale were used to assess associations of eligibility limits and stage-specific survival, adjusting for the effects of sex, metropolitan statistical area, comorbidities, year of diagnosis, facility type and volume, and state. RESULTS: Among patients with newly diagnosed cancer age 18-64 years, patients living in states with lower Medicaid income eligibility limits had worse survival for most cancers in both early and late stages, compared with those living in states with Medicaid income eligibility limits ≥ 138% FPL. A dose-response relationship was observed for most cancers with lower income limits associated with worse survival (13 of 17 cancers evaluated for early-stage cancers, and 11 of 17 cancers evaluated for late-stage cancers, and leukemia and brain tumors with P-trend < .05). CONCLUSION: Lower Medicaid income eligibility limits were associated with worse long-term survival within stage; increasing Medicaid income eligibility may improve survival after cancer diagnosis.