Adherence to pro-vegetarian dietary patterns and gastric cancer risk: a pooled analysis of the StoP Consortium

Pro-vegetarian (PVG) diets may reduce gastric cancer (GC) risk, but evidence remains limited. We aimed to evaluate the association between three predefined PVG patterns-general (gPVG), healthful (hPVG), and unhealthful (uPVG)-and GC risk stratifying by sex in the context of the Stomach Cancer Pooling (StoP) Project Consortium.

We analysed data from six case-control studies from the StoP Consortium. The final sample included 1,857 incidents, histologically confirmed GC cases and 5,646 controls. Food intakes were assessed using country-specific food frequency questionnaires, which allowed the estimation of PVG patterns using established scoring methods. Adherence to PVG dietary patterns was classified into quintiles. Logistic mixed models with random intercepts for each study were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

Compared to the lowest quintile, the highest quintile of adherence to gPVG was associated with an OR_Q5vsQ1 = 0.61 (95% CI: 0.50-0.75; p-trend =  < 0.001) and the hPVG was associated with an OR_Q5vsQ1 = 0.66 (0.54-0.80; p-trend =  < 0.001). The uPVG pattern was associated with an OR_Q5vsQ1 = 1.27 (1.05-1.55; p-trend = 0.013). The inverse association for gPVG was more evident in men, OR_Q5vsQ1 = 0.56 (0.43-0.73) than in women, OR_Q5vsQ1 = 0.73 (0.53-1.01); for the hPVG pattern, a significant inverse association was only observed in women, OR_Q5vsQ1 = 0.50 (0.36-0.69); and, for the uPVG pattern, the increased GC risk was only observed in women, OR_Q5vsQ1 = 1.70 (1.25-2.32).

Higher adherence to gPVG and hPVG dietary patterns is associated with lower GC risk, whereas higher adherence to uPVG is associated with increased risk. The inverse association observed for hPVG pattern and the positive association for uPVG were only observed in women. These differential effects of dietary patterns in men and women deserve to be further investigated.