Body mass index and gastric cancer risk: results from the Stomach Cancer Pooling Project Consortium.

Body mass index (BMI) has been associated with gastric cancer (GC), though results are conflicting regarding the GC subsites of cardia and non-cardia. This study aims to evaluate the associations between BMI and GC risk, focusing on these distinct anatomical subsites. We pooled data from seven case-control studies from the Stomach Cancer Pooling (StoP) Project. Pooled odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) of GC risk across BMI categories (normal weight, overweight, obesity) were calculated by pooling study-specific ORs through random-effects meta-analytic models. The dose-response relationship between BMI and the risk of GC cancer was assessed by using a one-stage mixed-effects logistic regression model. Results were stratified according to cardia and non-cardia GC. The analysis comprised 1478 GC cases, including 511 cardia and 967 non-cardia cases, and 6671 controls. There was an increased risk of cardia GC among obese patients (OR 1.57, 95% CI 1.20-2.06), while no association was found for non-cardia GC (OR 0.82, 95% CI 0.66-1.01). Restricting the analysis to population-based studies, the association for cardia GC became stronger for obese (OR 1.65, 95% CI 1.09-2.48) and overweight (OR 1.62, 95% CI 1.10-2.39) patients. The dose-response meta-analysis showed an increased risk of cardia GC with increasing BMI values, ranging from a null effect at a BMI of 21.75 to an OR of 2.06 (95% CI 1.22-3.48) for a BMI of ≥40. Our results indicate an association between higher BMI categories and the risk of cardia GC, whereas no association was found with non-cardia GC.