Waist circumference, body mass index, and colorectal cancer risk according to diabetes status: A Korean nationwide population-based cohort study

Background and Aim We investigated the relationship of BMI and waist circumference with the risk of colorectal cancer (CRC) using a population-based cohort database and to explore the relationship of CRC with diabetes status. Methods Retrospective data (age >20 years) on anthropometric variables, blood parameters of fasting sugar, lipid levels, and blood pressure were collected from the National Health Insurance Corporation database between 2009 and 2012. Cox regression models were used to estimate hazard ratio (HR) and corresponding 95% confidence intervals (95% CI). Results Of the 23 121 360 people studied, 120 579 were diagnosed with CRC after a median follow-up period of 5.4 years. Both waist circumference and body mass index were positively associated with increased risk of CRC, regardless of age or sex. After mutual adjustment, only waist circumference was significantly associated with increased risk of CRC (HR = 1.275, 95% CI: 1.205-1.349). When the risk of CRC was compared according to diabetes status among people with the same waist circumference range, risk of CRC was higher for those with worse diabetes status. Conclusion When waist circumference and body mass index were mutually adjusted, only waist circumference was associated with CRC risk. In addition, the risk of CRC is gradually higher in those with worsening diabetes, even if their waist circumferences are within the same range.