PROJECT SUMMARY Background: Prostate cancer screening with prostate-specific antigen (PSA) testing only modestly reduces the number of deaths at the expense of increasing the morbidity associated with overdiagnosed cases and unnecessary treatment. As a result, clinical guidelines recommend against universal PSA screening for men but do call for shared decision making (SDM). SDM involves discussing the benefits and harms of interventions and incorporating patient preferences into decisions. Effective SDM requires healthcare systems-level support, promotion of SDM skills for practitioners and patients, as well as context-specific knowledge for all involved. Without proper planning for and support for providers to implement SDM and patients to participate, such guideline-recommended discussions cannot be expected. Meanwhile, the next frontier in cancer screening is a new paradigm of precision screening, in which an individual’s genetic make-up may be used to stratify their level of future cancer risk and inform whether, how early, and how often they should be screened. Polygenic risk scores (PRS) are composite risk estimates derived from large, population-based genome-wide association studies. The goal of incorporating PRS into population screening is to reduce the harms of overdiagnosis and unnecessary treatment for low-risk individuals while preserving screening benefits for those at highest risk. Significance: Both precision screening and SDM are major pillars of the new White House Cancer Moonshot v2.0. PRS-informed prostate cancer screening is likely to be the first of these precision screenings within the Veterans’ Health Administration (VHA). Our project is also clearly aligned with VHA’s patient-centered learning initiative to turn VHA into a health literate care organization. Innovation and Impact: This clinical innovation will have direct impact on primary care, where cancer screening decisions are made. The limited genetic counseling workforce is not sufficient to offload all conversations about PRS from patient-aligned care teams (PACTs) in which primary care providers (PCPs) work. The potential effect of PRS-guided screening on equity is also a concern. Current guidelines consider Black race risk factor that might favor PSA screening, as Black men are twice as likely to die of prostate cancer than white men. Any new screening paradigm must consider existing disparities and a historical context of racial discrimination and mistrust for a prostate cancer PRS is to be accepted among racially diverse patients. Specific Aims: To proactively address VHA’s needs in implementing a prostate cancer PRS using SDM into primary care, we propose the following aims: 1) Qualitatively describe Veterans’ decision support needs to discuss PRS and use them in SDM about prostate cancer screening; 2) Qualitatively describe and quantitatively determine the perceived competency, perceived barriers, and informational and support needs for implementing SDM aroun...