Association between body mass index and gastric cancer risk according to effect modification by helicobacter pylori infection

Abstract

<i>Purpose</i> - Few studies investigated roles of body mass index (BMI) on gastric cancer (GC) risk according to <i>Helicobacter pylori</i> infection status. This study was conducted to evaluate associations between BMI and GC risk with consideration of <i>H. pylori</i> infection information.<p><p>

<i>Materials and Methods</i> - We performed a case-cohort study (n=2,458) that consists of a subcohort, (n=2,193 including 67 GC incident cases) randomly selected from the Korean Multicenter Cancer Cohort (KMCC) and 265 incident GC cases outside of the subcohort. <i>H. pylori</i> infection was assessed using an immunoblot assay. GC risk according to BMI was evaluated by calculating hazard ratios (HRs) and their 95% confidence intervals (95% CIs) using weighted Cox hazard regression model.<p><p>

<i>Results</i> - Increased GC risk in lower BMI group (< 23 kg/m²) with marginal significance, (HR, 1.32; 95% CI, 0.98 to 1.77) compared to the reference group (BMI of 23-24.9 kg/m²) was observed. In the <i>H. pylori</i> non-infection, both lower (< 23 kg/m²) and higher BMI (≥ 25 kg/m²) showed non-significantly increased GC risk (HR, 10.82; 95% CI, 1.25 to 93.60 and HR, 11.33; 95% CI, 1.13 to 113.66, respectively). However, these U-shaped associations between BMI and GC risk were not observed in the group who had ever been infected by <i>H. pylori</i>.<p><p>

<i>Conclusion</i> - This study suggests the U-shaped associations between BMI and GC risk, especially in subjects who had never been infected by <i>H. pylori</i>.