The role of tomato products and lycopene in the prevention of gastric cancer: a meta-analysis of epidemiologic studies.

Abstract Background Gastric cancer is the second most common cause of death from cancer worldwide. Epidemiologic studies have examined the possible association between tomato products consumption and gastric cancer, but the relationship between tomato products and the risk of gastric cancer is controversial. We performed a meta-analysis of cohort and case–control studies to analyze this association. Methods We systematically searched MEDLINE and EMBASE and contacted authors to identify potential studies published from January 1966 to June 2012. We pooled the relative risks from individual studies using a random-effects model and performed heterogeneity and publication bias analyses. Results Twenty-one studies were eligible for our inclusion criteria, in a pooled analysis of all studies, consumption of large amounts of tomato products (in a comparison of the highest and lowest consumption groups) reduced the risk for gastric cancer (odds ratio, 0.73; 95% confidence interval, 0.60–0.90). The pooled OR of lycopene consumption and serum lycopene was 0.88 (95% CI = 0.67–1.16) and 0.79 (95% CI = 0.59–1.07), respectively. Conclusions Consumption of large amounts of tomato products is associated with a reduced risk of gastric cancer. However, because of potential confounding factors and exposure misclassification, further studies are required to establish these findings.