Cruciferous vegetable consumption and gastric cancer risk: a meta-analysis of epidemiological studies

The relationship between consumption of cruciferous vegetables (CV) and risk of gastric cancer has been investigated by many studies, but remains controversial. We carried out a meta-analysis to summarize available evidence from epidemiological studies on this point. Relevant published reports of CV intake and gastric cancer were identified using MEDLINE (PubMed), EMBASE, and Web of Science databases through to the end of September 2012. We pooled the relative risk from individual studies using a fixed- or random-effects model and carried out heterogeneity and publication bias analyses. Sixteen case-control and six prospective studies were included in our analysis. When all studies were pooled, we yielded a significantly inverse association between CV (relative risk = 0.81; 95% confidence interval, 0.75-0.88) intake and gastric cancer risk, with little heterogeneity (Q = 27.27, P = 0.292, I(2) = 12.0%). Specific analysis for cabbage intake yielded similar result. When separately analyzed, case-control studies of CV intake yielded significant results and the results of prospective studies showed borderline statistical significance. Moreover, significant results were consistent for high-quality studies, for North American, European, and Asian studies, for studies on males, and for studies on non-cardia gastric cancer. Findings from this meta-analysis provide evidence that high intake of CV was inversely associated with the risk of gastric cancer and non-cardia gastric cancer in humans. Further studies on other specific CV, food preparation methods, and stratified results by anatomic cancer site and histological type should be extended in the future.