Clinical and biological characteristics of colorectal cancer with familial predisposition

Objective:To evaluatethemicrosatelliteinstability(MSI),expressionof mismatchrepair(MMR)gene(hMLH1,hMSH2)andproliferationkineticsincolorectalcancer(CRC)withfamilialpredisposition.Method:Forty-sixcasesof CRC were studiedusingsilverstainingpolymerasechainreaction-singlestrandconformation polymorphism(PCR-SSCP)technique,streptavidin-peroxidase(SP)immunohistochemicalmethodand flowcyto-metry.Results:In CRCpatientswithfamilialpredisposition,theMSI-positiveratewas higherthanin sporadicCRC(P<0.05).FamilialpredispositionandpositiveMSIwerestronglyrelatedto earlyageof canceronset,theproclivity for proximalcoloniccancer,poordifferentiatedandextracolorectalnmalignancies(P<0.01,P<0.05).Theincidence of negativeexpressionof hMLH1intumortissueandhMLH1,hMSH2innormalcolorectaltissueswassignificantly higher(P<0.05).Thenegativeexpressionof hMLH1togetherwithhMSH2was relatedwithpositiveMSI(P<0.05).InMSI-positiveCRCcells,theproliferationcellnucleusantigen(PCNA)expression,proliferationindexandS-phase cellsdecreasedobviously(P<0.01,P<0.05).Conclusion:In CRCwithfamilialpredisposition,MSI mightbe an importantcontributor.Therateof hMLH1andhMSH2mutationincreasedintumorandnormaltissue,andtheproli-ferationactivityof theircancercellwaslower.