Beyond smoking: A geospatial investigation of factors associated with lung and bronchus cancer risk in Pennsylvania

Introduction: While smoking is the leading cause of lung and bronchus cancer (LBC), additional exposures have been implicated and may explain the rise in LBC among never-smokers. To better understand the spatial distribution of LBC incidence and associated risk factors, this study aims to identify geographic areas with significantly elevated incidence rates in Pennsylvania and investigate the potential underlying risk factors. Methods: Using cancer registry data aggregated to the census tract level, spatial scan statistics were applied to detect areas of higher-than-expected LBC incidence across the state. Associations were then tested between census tract inclusion in a high-incidence area and eight area-level risk factors, including behavioral (e.g., smoking prevalence), environmental (e.g., PM_2.5), built environment (e.g., traffic density, housing age), and socioeconomic (e.g., poverty, race) and occupational (e.g., construction work) characteristics. Results: Twenty-two geographic areas of higher-than-expected LBC incidence were identified. Smoking rates, PM_2.5, traffic density, old homes, and population density were found to be positively associated with inclusion in one of these areas. All high LBC areas had higher rates of smoking than the remainder of Pennsylvania, 20 were also high on PM_2.5, traffic, or both; 19 had elevated rates of old housing. Conclusion: By evaluating multiple factors simultaneously, this study provides a more nuanced understanding of how exposures interact to shape geographic variation in LBC incidence. This multifactorial, spatially explicit approach also assesses whether area-based environmental and socioeconomic risks contribute to LBC burden independently of smoking rates, thus informing targeted prevention strategies and future research.