Abdominal obesity increases risk for esophageal cancer: a nationwide population-based cohort study of South Korea

Background The relationship between overall obesity, as measured by body mass index (BMI) and risk of esophageal squamous cell carcinoma (ESCC) has been reported to show a negative correlation. However, the relationship of ESCC, which accounts for around 90% of esophageal cancers in South Korea, with abdominal obesity, as measured by waist circumference (WC), may be different. Thus, we investigated the association between abdominal obesity and esophageal cancer in a nationwide population-based cohort. Methods A retrospective cohort study of 22,809,722 individuals who had undergone regular health check-ups provided by the National Health Insurance Corporation between 2009 and 2012 (median follow-up period, 6.4 years) in South Korea was conducted. Abdominal obesity was defined as a WC[ 90 cm for men and[ 85 cm for women. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) using chi(2) test and Cox proportional hazards model adjusted for confounding factors. The primary outcome was newly developed esophageal cancer. Results After adjusting for BMI, abdominal obesity increased the risk of esophageal cancer (HR 1.29, 95% CI 1.23-1.36). WC increased the risk for esophageal cancer in a dose-dependent manner (p values for trend < 0.0001). Among overweight (BMI 23-24.9 kg/m(2)) and obese I (BMI 25-29.9 kg/m(2)) individuals, abdominal obesity was a risk factor for esophageal cancer (HR 1.22, 95% CI 1.11-1.34; HR 1.28, 95% CI 1.18-1.39, respectively). Conclusion Increasing abdominal obesity may be associated with an increased risk for esophageal cancer. Further studies are warranted to confirm the relationship.