BACKGROUND Dual-eligibility status for both Medicare and Medicaid is associated with unfavorable cancer stage outcomes. However, given the reduced financial barriers, duals enrolled in Medicaid prior to cancer diagnosis-or those using Medicaid as a supplemental health insurance program (Dual/SHIP)-may have improved access to preventive services compared with low-income nonduals (LI/nondual), therefore, be more likely to be diagnosed at earlier stages of cancers amenable to screening. OBJECTIVES To compare breast, prostate, and colorectal cancer stage at diagnosis between Duals/SHIP and LI/nonduals, adjusting for sociodemographic variables, comorbidities, and nursing home status. RESEARCH DESIGN Cross-sectional study using a database developed by linking records from the Ohio Cancer Incidence Surveillance System with Medicare and Medicaid files, as well as US census data. SUBJECTS Fee-for-service, Ohio residents aged 65 years or older, and diagnosed with incident breast, prostate, or colorectal cancer in 1997-2001. MEASURES (1) Unknown stage/unstaged cancer and (2) distant-stage cancer at diagnosis. RESULTS Duals/SHIP were more likely than LI/nonduals to have unknown stage/unstaged breast cancer (adjusted odds ratio: 1.43, 95% Confidence Interval (CI): 1.02-2.0; P = .035). However, this difference was not seen in prostate or colorectal cancer. In prostate cancer patients, but not in breast or colorectal cancer patients, Dual/SHIP status was associated with distant-stage disease (adjusted odds ratio: 1.74, 95% CI: 1.12-2.70; P = .014). In colorectal cancer patients, dual status was not associated with cancer stage. CONCLUSION The findings show no benefit associated with Medicaid as SHIP. Rather, they indicate that for the most part, cancer stage is comparable between Duals/SHIP and LI/nonduals.