Cancer morbidity and mortality is greatly reduced through screening and prevention, but uninsured patients are much less likely than insured patients to receive these evidence-based services as recommended. In addition, uninsured cancer survivors receive fewer primary and preventive care services than those with health insurance. Thus, it is hypothesized that Affordable Care Act (ACA) Medicaid expansions could substantially improve access to essential cancer preventive and screening services for previously uninsured patients, and facilitate better care for cancer survivors who gain health insurance. In 2012, the United States (US) Supreme Court ruled that states were not legally required to implement ACA Medicaid expansions, creating a unique natural experiment to test this hypothesis. By April 1, 2015, 30 states and the District of Columbia had implemented expansions, and 20 states had not. This led to increased Medicaid enrollment by 26% in expansion states, compared to 8% in non-expansion states. Previous single-state Medicaid expansions led to increased utilization of healthcare services and improved health outcomes post-expansion. For example, in Oregon, cervical cancer screening rates were 18-19% higher among women who gained Medicaid in 2008, compared to those who remained uninsured. However, no previous assessments of state-specific expansions had concurrent control (non-expansion) states for comparison. Further, little is known about how Medicaid expansion impacts the delivery of recommended primary and preventive care services to cancer survivors, termed 'survivor care.'