Helicobacter pylori and Pancreatic Cancer Risk: a Metaanalysis Based on 2,049 Cases and 2,861 Controls

Aim: Helicobacter pylori (H. pylori) have been considered as a risk factor for many cancers. We conducted thismeta-analysis to clarify the association between H. pylori infection and the risk of pancreatic cancer.
Methods: Wesearched the Medicine/Pubmed and Embase databases, studies about the association between H. pylori infectionand pancreatic cancer published up to Jan.2014 were included. Finally, a total of 9 studies were used for this ameta-analysis. The odds ratios (ORs) and 95% confidence interval (95%CI) of H. pylori infection on pancreaticcancer with respect to control groups were evaluated. Two authors independently assessed the methodologicalquality and extracted data. This meta-analysis was conducted using software, state (version 12.0) to investigateheterogeneity among individual studies and to summarize the studies. Using the fixed-effects or random-effectsmodel, depending on the absence or presence of significant heterogeneity. Sensitivity analysis was performed toassess the influence of each individual study on the pooled ORs by omitting a single study each time. Publicationbias was evaluated by funnel plot, using Egger’s and Begg’s tests.
Results: There was no significant associationbetween H. pylori infection and pancreatic cancer risk in the summary ORs,(OR=1.06, 95%CI: 0.74-1.37)through the random-effect method, but heterogeneity among studies was significant (I2=58.9%), so we putthe studies into two subgraphs (eastern and western). The results about western (OR=1.14 95%CI:0.89, 1.40)showed heterogeneity among the western countries of I2=6.6%, with no significant association between Hp+and pancreatic cancer, but the eastern countries (OR=0.62, 95%CI:0.49, 0.76), I2=0, suggested that decreasingpancreas-cancer risk in subjects with Hp+ infection. Simultaneously, 7 studies examined CagA+ strains was(OR=0.84 95%CI:0.63, 1.04), I2=36% with the random-effect method, subgraphs indicated that CagA+ coulddecrease the risk of pancreatic cancer in the eastern subjects (OR=0.66, 95%CI:0.52-0.80), but the associationwas not statistically significant in the western subjects (OR=0.95, 95%CI:0.73, 1.16).
Conclusion: Hp+ andCagA+ infection are associated with a decreased risk of pancreatic cancer in eastern populations but have nosignificant associations in western countries.