Geographic, sex and socioeconomic disparities in esophageal cancer incidence in China: A population-based study

Geographic and sex differences in esophageal cancer have been reported in China, but data are lacking at the local level. We aimed to investigate geographic and sex disparities in esophageal cancer incidence among Chinese counties and whether county-level socioeconomic status was associated with these variations. We obtained esophageal cancer data from 2015 to 2017 for 782 counties from population-based cancer registries in China. We calculated age-standardized incidence rates and male-to-female incidence rate ratios (IRRs) by county. We performed hotspot analysis to identify geographical clusters. We used negative binomial regression models to analyze the association between incidence rates and county-level socioeconomic factors. There were significant geographic disparities in esophageal cancer incidence, with 8.1 times higher rate in the 90th-percentile county than in the 10th-percentile county (23.7 vs 2.9 per 100 000 person-years). Clusters of elevated rates were prominent across north-central China. Nationally, men had 2.9 times higher incidence of esophageal cancer than women. By county, the male-to-female IRRs ranged from 1.1 to 21.1. Clusters of high male-to-female IRRs were observed in northeast China. Rurality (IRR 1.16, 95% CI 1.10-1.22), per capita gross domestic product (IRR 0.95, 0.92-0.98) and percentage of people with a high school diploma (IRR 0.86, 0.84-0.87) in a county were significantly associated with esophageal cancer incidence. The male-to-female IRRs were higher in counties with higher socioeconomic status. Substantial differences in incidence rates and sex ratios of esophageal cancer exist between Chinese counties, and county-level socioeconomic status was associated with these variations. These findings may inform interventions to reduce these disparities.