Helicobacter pylori infection and normal colorectal mucosaadenomatous polyp- adenocarcinoma sequence: a metaanalysis of 27 case- control studies

AimThe study aimed to determine whether Helicobacter pylori infection is associated with colorectal adenocarcinoma and to quantify the extent of the risk. MethodA literature search was performed to identify studies published between 1995 and 2012 for relevant risk estimates. Fixed and random effect meta-analytical techniques were conducted for colorectal adenocarcinoma and adenomatous polyp. ResultsTwenty-seven case-controlled studies involving 3450 adenocarcinoma patients, 1304 adenomatous polyp patients and more than 4000 controls were included. Helicobacter pylori was associated with an increased risk of colorectal adenocarcinoma and adenomatous polyp [odds ratio (OR) 1.24, 95% CI 1.12-1.37, P=0.66; OR 1.87, 95% CI 1.53-2.28, P=0.81]. There was a significant association between the CagA-positive strain and adenocarcinoma risk (OR 1.22, 95% CI 1.08-1.37, P=0.05). In addition, there was an increased risk of tubular adenoma and villous adenoma formation (OR 3.06, 95% CI 1.98-4.73, P=0.14; OR 2.05, 95% CI 0.84-4.97, P=0.86). ConclusionThe meta-analysis suggests a promoting effect of Helicobacter pylori on the risk of adenocarcinoma. It also suggests that Helicobacter infection might have its influence at the start of the adenomatous polyp disease sequence.