PROJECT SUMMARY Disparities in outcomes among cancer patients who are rural-residing, with lower SES, and a racial minority are well-documented and have garnered significant national media attention. Recent retrospective cohort studies reported minimal rural/urban and racial disparities in outcomes when patients had uniform access to care, highlighting the critical clinical importance of standardizing access to cancer care. Data made available which evaluates access to specialists typically determines access based on a per capita count of individual specialties, which does not adequately capture access to interdisciplinary teams of specialists. A relatively unexplored area of study is the extent to which relationships between cancer specialists can be characterized and then targeted to standardize access to cancer care, reduce cancer health disparities, and improve patient outcomes. By assessing the relationships between physicians based on patient-sharing and geographic proximity patterns observed in administrative data, we propose to apply our team’s expertise in network analysis and cancer care to provide a framework for evaluating patient access to cancer care which recognizes the coordination across medical oncology, radiation, and surgical specialists. We aim to develop and apply a novel network measure– linchpin centrality – which identifies cancer specialists who are the only specialist of their kind among their neighbors’ ties. We propose to evaluate variation of physician linchpin centrality by cancer patient race and geographic variables, building on previous work demonstrating that racial disparities vary significantly across US cities and rural subregions. We will further evaluate associations between physician linchpin centrality and timely treatment and cancer mortality. One avenue for increasing access to specialist care is through cancer specialists traveling to a secondary practice location, typically a rural hospital in a community too small to support a full-time specialist. However, little is known about the impact of traveling physicians on existing relationships between physicians and patient access to coordinated cancer care, a gap in knowledge our proposal will address. In analyses specific to rural areas, we will assess the extent to which physician travelers impact physician network structure and patient outcomes. Finally, we will conduct a qualitative study to inform further development of linchpin centrality and a network algorithm as an intervention to improve cancer care. The algorithm we develop will provide health systems with actionable data on the organization of cancer care providers for their catchment and can help guide interventions and allocate resources appropriately. In conclusion, this proposal uses network analysis to capture essential characteristics of the quality of care for cancer patients, with the goal of bridging theory and practice to improve access and outcomes with a network-guided intervention.

PROJECT NARRATIVE A key objective in efforts to reduce cancer health disparities is standardizing access to care. This proposal aims to develop a novel physician network-based measure characterizing access to specialist cancer care and investigate how this knowledge can be used to reduce rural, racial, and socioeconomic disparities in patient outcomes for breast, colorectal, and lung cancer patients. We will use these results to bridge theory and practice by developing a data-driven algorithm that would deliver to health systems approaches for establishing more robust physician networks and improve patient outcomes.