Consumption of vegetables may reduce the risk of liver cancer: results from a meta-analysis of case-control and cohort studies.

PURPOSE:We conducted a meta-analysis of all published case-control and cohort studies to evaluate the relationship between vegetables intake and liver cancer risk. METHODS:We searched for cohort and case-control studies published before February 2014, using Pubmed and Cochrane Library Central database. Pooled relative risk (RR) estimates and corresponding 95% confidence interval (CI) were calculated using the inverse-variance method. RESULTS:Eight case-control studies and one cohort study were included in this meta-analysis, involving a total of 136,425 subjects and 1349 liver cancer cases. Finally, we observed a statistically significant protective effect of vegetables consumption on liver cancer (RR=0.78, 95% CI [0.62, 0.99]). In the present meta-analysis, no publication bias was observed among studies using Begg's P value (P=0.532); Egger's (P=0.180) test, which suggested there was no evidence of publication bias. CONCLUSIONS:Our results suggest that vegetables consumption may reduce the risk of liver cancer. More prospective cohort studies with larger sample size, well-controlled confounding factors are warranted to further evaluate the association.