METHODS: A retrospective analysis was performed utilizing Syapse’s Learning Health Network^TM, an electronic medical record derived database comprising cancer care data from multiple care settings within CHS across 33 states, 450+ hospitals and 1,900+ oncologists. Patients included: those >18 yo; stage IIIB, IIIC, or IV non-small cell lung cancer OR early stage diagnosis with recurrence/progression on or after 1/1/2015; >1 patient encounter within 90 days of advanced diagnosis; received an ICI (nivolumab, pembrolizumab, or atezolizumab) before 7/1/2017; and data were reviewed by Syapse Certified Tumor Registrars. The first ICI received by each patient was assessed over time.