Helicobacter pylori infection and colorectal cancer risk: evidence from a large population-based case-control study in Germany.

Evidence concerning the role of Helicobacter pylori infection in the development of colorectal cancer remains controversial. The authors assessed the association of H. pylori seroprevalence with risk of colorectal cancer in a large population-based case-control study from Germany in 2003-2007. Serum antibodies to H. pylori in general and the cytotoxin-associated gene A protein (CagA) were measured in 1,712 incident colorectal cancer cases and 1,669 controls. The association between H. pylori seroprevalence and colorectal cancer risk was estimated by logistic regression, with adjustment for potential confounders and stratification by age group, sex, anatomic subsites, and cancer stage. Overall, H. pylori seroprevalence was higher in cases (46.1%) than in controls (40.1%), resulting in an age- and sex-adjusted odds ratio of 1.30 (95% confidence interval (CI): 1.14, 1.50). Adjustment for established colorectal cancer risk factors decreased the odds ratio to 1.26 (95% CI: 1.09, 1.47), with a further reduction to 1.18 (95% CI: 1.01, 1.38) after additional adjustment for previous colorectal endoscopy. Stratified analyses showed risk elevation to be essentially confined to left-sided colorectal cancer, with an odds ratio of 1.22 (95% CI: 1.02, 1.45), suggesting that H. pylori infection may be associated with a small yet relevant risk increase in the left colorectum.