Background: Colorectal cancer (CRC) is the 2nd leading cause of cancer death in the US. Screening reduces incidence and mortality, in part due to detection and removal of polyps such as adenomas. Guidelines recommend surveillance colonoscopy after adenoma removal (“polypectomy”), but incremental benefit of surveillance after polypectomy on reducing CRC risk is uncertain. For adults age 75 and older (“older adults”) considering surveillance colonoscopy, these issues are of particular importance. Harms associated with colonoscopy increase dramatically with age. Older adults are less likely to live long enough to benefit from interventions such as surveillance colonoscopy due to competing non-CRC mortality risks. The well- established age-related increasing risks for competing causes of mortality and colonoscopy-related harms stand in sharp contrast to major evidence gaps; it is unclear whether CRC risk is clinically significant among older adults with prior history of polyps, and whether exposing older adults to surveillance reduces CRC risk. Yet, the default clinical paradigm is for many older adults to receive surveillance colonoscopy. Significance: In the Department of Veterans Affairs (VA), surveillance is a very common indication for colonoscopy among older Veterans, with an estimated 17,400 exposed to surveillance annually. The mismatch between available evidence and current clinical practice, coupled with extreme constraints on colonoscopy resources in the VA make the surveillance colonoscopy paradigm an ideal focus area for quantifying risks and benefits in order to optimize health outcomes. Innovation & Impact: Establishing CRC risk among older adults with prior polypectomy and outcomes associated with surveillance will fill critical evidence gaps. Multi-stakeholder perspectives on CRC risk and surveillance outcomes will pave the way for future implementation of evidence- based, Veteran-centric, and optimized-value strategies for surveillance among older adults. This work will also serve as a model for leveraging VA data to address an important population health challenge for the VA’s large and growing older adult population and how to use these data to engage Veterans to optimize outcomes. Specific Aims: Aim 1) Compare cumulative CRC risk after age 75 in a cohort of older adults with history of normal colonoscopy (n=101,328) vs. colonoscopy with polypectomy (n=29,548) prior to age 75. Hypothesis: Cumulative risk for incident CRC (primary analysis) and fatal CRC (secondary analysis) after age 75 will be similar among older adults who had normal colonoscopy vs. colonoscopy with polypectomy prior to age 75. Aim 2) Assess comparative effectiveness of exposure vs. no exposure to surveillance for reducing CRC risk. Hypothesis: Older adults unexposed vs. exposed to surveillance will have similar risk for incident CRC (primary analysis) and fatal CRC (secondary analysis). Aim 3) Obtain multi-level stakeholder perspectives regarding CRC risk and s...