Helicobacter pylori infection and colorectal cancer risk: a meta-analysis.
BACKGROUND
Several studies suggested an association between Helicobacter pylori infection and colorectal carcinoma or adenoma risk. However, different authors reported quite varying estimates. We carried out a systematic review and meta-analysis of published studies investigating this association and paid special attention to the possibility of publication bias and sources of heterogeneity between studies.


METHODS
An extensive literature search and cross-referencing were performed to identify all published studies. Summary estimates were obtained using random-effects models. The presence of possible publication bias was assessed using different statistical approaches.


RESULTS
In a meta-analysis of the 11 identified human studies, published between 1991 and 2002, a summary odds ratio of 1.4 (95% CI, 1.1-1.8) was estimated for the association between H. pylori infection and colorectal cancer risk. The graphical funnel plot appeared asymmetrical, but the formal statistical evaluations did not provide strong evidence of publication bias. The proportion of variation of study results because of heterogeneity was small (36.5%).


CONCLUSIONS
The results of our meta-analysis are consistent with a possible small increase in risk of colorectal cancer because of H. pylori infection. However, the possibility of some publication bias cannot be ruled out, although it could not be statistically confirmed. Larger, better designed and better controlled studies are needed to clarify the situation.
Zumkeller
Natalia
N
Department of Epidemiology, German Centre for Research on Ageing, Heidelberg, Germany.
Brenner
Hermann
H
Zwahlen
Marcel
M
Rothenbacher
Dietrich
D
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000209:etiology*; D016481:Helicobacter Infections / Q000150:complications*; D016480:Helicobacter pylori; D006801:Humans; D008875:Middle Aged; D016017:Odds Ratio; D017594:Publication Bias; D012307:Risk Factors