The Effect of Social Deprivation and Smoking on the Incidence and Mortality of Lung Cancer in North Carolina: Implications for Lung Cancer Screening

##Background Socioeconomic deprivation (SD) has been associated with lung cancer incidence. The extent to which this relationship is mediated by smoking prevalence remains unclear. ##Methods We conducted a cross-sectional analysis of county-level data in North Carolina. SD was measured using the County Deprivation Index (CDI). Causal mediation analysis was performed to assess whether smoking prevalence mediates the relationship between CDI and lung cancer incidence. ##Results The mean age-adjusted incidence rate of all-stage lung cancer was 66.5 cases per 100,000 (range: 44.6–91.8), and for late-stage cancer, 68.7 cases per 100,000 (range: 32.9–117.3). Rural counties had significantly higher incidence rates for both outcomes. CDI was positively associated with all-stage (β = 10.54; P < .0001) and late-stage (β = 8.40; P < .0001) lung cancer. In mediation analysis, 61.5% of the total effect of CDI on all-stage lung cancer incidence was attributable to smoking prevalence (indirect effect = 6.73 per 100,000; P = .0126). A similar pattern was observed for late-stage disease (indirect effect = 5.36 per 100,000; P = .0073). Direct effects were not statistically significant. ##Limitations Associations at the county level may not reflect relationships at the individual level. The CDI may not fully capture all relevant structural determinants of health. Our causal mediation analysis assumes a unidirectional pathway from SD to smoking prevalence to lung cancer incidence. ##Conclusions Smoking prevalence explained a substantial proportion of the relationship between SD and lung cancer burden at the county level. These findings suggest that deprivation may independently contribute to lung cancer risk.