EversinceHelicobacterpylori（H.pylori）wasrecognizedasaninfectiouscauseofgastriccancer,therehasbeenincreasinginterestinexaminingitspotentialroleincolorectalcarcinogenesis.Datafromcasecontrolandcross-sectionalstudies,mostlyrelyingonhospital-basedsamples,andseveralmeta-analyseshaveshownapositivestatisticalrelationshipbetweenH.pyloriinfectionandcolorectalneoplasia.However,thepossibilityexiststhattheresultshavebeeninfluencedbybias,includingtheimproperselectionofpatientsanddisparitieswithrespecttopotentialconfounders.Whiletheevidencefallsshortofadefinitivecausallink,itappearsthatinfectionwithH.pylori/H.pylori-relatedgastritisisassociatedwithanincreased,althoughmodest,riskofcolorectaladenomaandcancer.Thepathogenicmechanismsresponsibleforthisassociationremainuncertain.H.pylorihasbeendetectedincolorectalmalignanttissues;however,thepossibilitythatH.pyloriisadirectactivatorofcoloniccarcinogenesisremainspurelyhypothetical.Ontheotherhand,experimentaldatahaveindicatedaseriesofpotentialoncogenicinteractionsbetweenthesebacteriaandcolorectalmucosa,includinginductionandperpetuationofinflammatoryresponses,alterationofgutmicrofloraandreleaseoftoxinsand/orhormonalmediators,suchasgastrin,whichmaycontributetotumorformation.
