Sex-specific effect of body mass index and fasting glucose on gastric cancer risk and all causes mortality; a cohort study of 5.17 million

Background: Simultaneous evaluation of sex-specific effect of body mass index (BMI) and hyperglycemia on the risk of gastric cancer has been rarely reported. Here, we investigated the sex-specific effect of BMI and hyperglycemia on gastric cancer. Methods: Persons who underwent National gastric cancer screening from 2006 to 2007 and had no gastric cancer at baseline, were enrolled and followed up to 2015. The risk of gastric cancer by BMI and glucose was measured using risk ratios (RRs) and 95% confidence intervals (CI). Adjusted Cox analysis was performed to evaluate the risk of death. Results: Gastric cancers developed in 29,775 of 5.17 million. In the adjusted analysis, low BMI (<18.5 kg/m²; RR, 1.44; 95% CI, 1.36–1.53) and high fasting glucose (≥126 mg/dL; RR, 1.09; 95% CI, 1.05–1.13) increased the risk of gastric cancer. In sex-specific analysis, its risk by BMI was modified L-shape with cut-off value of 23 kg/m² in men and 18.5 kg/m² in women. Low BMI increased gastric cancer risk in men (RR, 1.39; 95% CI, 1.30–1.50) and women (RR, 1.48; 95% CI, 1.33–1.64). High fasting glucose increased the risk of gastric cancer in women (RR, 1.19; 95% CI, 1.11–1.28), but not in men. Low BMI increased all-cause mortality with cut-off value of 23 kg/m² in men and 18.5 kg/m² in women. Conclusions: Gastric cancer risk and all-cause mortality by BMI was L-shape with sex-specific cut-off value. The effect of fasting glucose on gastric cancer risk was different by sex.