Watch-and-waitapproachversussurgicalresectionafterchemoradiotherapyforpatientswithrectalcancer(theOnCoReproject):apropensity-scorematchedcohortanalysisLancetOncolPublishedOnlineDecember16,20151.Watch-and-waitapproachversus2004.10,AnnalsofSurgery,Habr-Gama.eg265patientswithdistalrectalweretreatedbyCRTwith5-FU,Leucovorinand5040cGyFive-yearOSandDFSrateswere88%and83%inResectionGroup,100%and92%inObservationGroup2.2004.10,AnnalsofSurgery,HabPurposeoncologicaloutcomesbetweenwatchandwaitandsurgicalresectionthesafetyofthewatch-and-wait3.PurposeoncologicaloutcomesbeThedefinitionofacCR(1)substantialdownsizingwithnoresidualtumororresidualfibrosisonly(2)nosuspiciouslymphnodesonMRI(3)noresidualtumoratendoscopyoronlyasmallresidualerythematousulcerorscar(4)negativebiopsiesfromthescar,ulcer,orformertumorlocation(5)nopalpabletumor,wheninitiallypalpablewithdigitalrectalexamination4.ThedefinitionofacCR(1)sMethodsone-to-onepairedcohortsofwatchandwaitversussurgicalresectionusingpropensity-scorematching（Tstage,age,andperformancestatus）primaryendpointwasDFSsecondaryendpointswasOSandcolostomy-freesurvival5.Methodsone-to-onepairedcohorMethodsCCRstandard:afterCRT8weeksormoreabsenceofresidualulceration,stenosis,ormasswithintherectumduringdigitalrectalexaminationandendoscopicexamination6.MethodsCCRstandard:afterCRTMethods259patientsfromatertiarycancercentreinManchester,UKbetweenJan14,2011andApril15,2013CCR--wait-and-seepolicygroup(31)NCCR--surgicalresection(228)7.Methods259patientsfromaterMethodsthreeneighbouringUKregionalcancercentres(LancashireandSouthCumbria,MerseysideandCheshire,andnorthWales)March10,2005,andJan21,2015--wait-and-seepolicygroup(98)8.MethodsthreeneighbouringUKMethodspreoperativechemoradiotherapy:45Gyin25dailyfractionswithconcurrentfluoropyrimidine-basedchemotherapyfor34days9.MethodspreoperativechemoradiMethodsDatainclude:TandNstages(MRI)Sex,age,BMISmokingstatus,performancestatusBaselineCEAHistologicalgradeHeightfromanalverge10.MethodsDatainclude:10.MethodsStatisticalanalysiscontinuousvariables--Kruskal-WallisandWilcoxonsigned-ranktestscategoricalvariables--χ2andMcNamaratestsPvalue11.MethodsStatisticalanalysis11.12.12.13.13.14.14.ResultsMedianfollow-upof33months(IQR19–43)44/129patientshadlocalregrowths(42patientshadmucosallesions,2patienthadsubmucosalormesorectallesions)15.ResultsMedianfollow-upof33Results16.Results16.Results31underwentsubsequentsalvagesurgeryTandNstages5ypT1,10ypT2,16ypT324ypN0,6ypN1,1ypN217.Results31underwentsubsequenResults18.Results18.Results19.Results19.Results20.Results20.Discussionanewoncologicalendpoint--non-regrowthdisease-freesurvivalthefirsttime--colostomy-freesurvival(1/4CCRavoidcolostomy)21.DiscussionanewoncologicalenDiscussionTwoadditionalfindingabout2/3nodepositiveassessedbyMRI,butdidnotaffectsubsequentendpoints9%(CCR)didnotreceivepreoperativechemotherapyanditsabsencedidnotaffectstudyendpoints22.DiscussionTwoadditionalfindiDiscussionlimitations1.follow-upwasrelativelyshort2.notrepresentativeofreal-worldoff-trialclinicalpractice3.isariskinpatientswithCCRmanagedbywatchandwait23.Discussionlimitations23.DiscussionStrengths1.largestreportedcohortoutside2.fromseveraltreatmentcentres3.astandardiseddefinition—CCR

24.DiscussionStrengths24.FuturePerspectivesNeedaprospectiverandomizedcontrolledtrialuniform

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