LRrecurrencerateswerestillunacceptablyhighanditwasnotuntil 1979whenHealdadvocatedforastrictdissectiontechniquethattheLR recurrenceratesstartedfalling,precipitously.Histechniquewasbased onaprogressiveresearchprovidingabetterunderstandingofthe

Thedistalresectionmargin(DRM)hasbeenapointofcontentionand debateamongcolonandrectalsurgeonsandsurgicaloncologists.Many beganquestioningthepreviousrecommendationsandguidelines requiringa5cmDRM.TheNationalSurgicalBreastandBowelProject foundnosignificantdifferencesinsurvivalorrecurrencewhen comparingDRMsoflessthan2cm,2–3cm,andhigherthan3cm. MoorepublishedaseriesfromMemorialSloanKetteringCancerCenter demonstratingthatintramuraltumorextensionbeyondthegross mucosaledgewasuncommonandusuallylessthan1cmafterthe preoperativecombined-modalitytherapy.Later,thesamegroupdeemed thata1cmmarginwasacceptableinpatientsinwhomsphincter preservationwasrequired.However,theauthorstillrecommends obtainingafrozensectionpathologicalreviewpriortoproceedingwith reconstruction.NewerargumentsbasedontheNorwegianColorectal CancerGrouphavenowrecommendedthatevenmoreimportantthana prognosticfactortowarddecreasedLRrecurrence,distantmetastasis, andoverallsurvivalisanegativecircumferentialmarginofgreaterthan2 mm.However,thesedataweremorestronglyprognosticinhigherlesions >6cmabovetheanalverge.

Currentstandardpractice,basedonpreoperativestaging,eitherwith

endorectalultrasonographyormagneticresonanceimaging(MRI), recommendslowanteriorresection(LAR)orAPRformostadvanced (i.e.,T3orN+)distallesions,within0–5cmabovethedentateline.All theadvancesinrectalsurgerydescribedhavebeenintegraltotheadvent ofintersphinctericrestorativeproctocolectomy(IRP),whilecontinuingto meettheaboveprimaryobjectives.Inthisprocedure,theinternalanal sphincter—acontinuationoftherectalwall—iscompletelyorpartially excisedtoobtainthenecessaryfull-thicknessDRM.Subsequentcoloanal anastomosistotheremainingsphinctercomplextherebyrestores intestinalcontinuity,withagoalofimprovedqualityoflifewhile preservingoncologicandfunctionaloutcomes.Withtheserefinements andimprovementsinbothneoadjuvantchemoradiationtherapyand surgicaltechniques,patientsnowhaveanotheroptionavailablefor sphincterpreservation.

Duetotheinherentmorbidityassociatedwithapermanentstoma,a restorativeproctocolectomymaybeofferedtoallpatientswithtumors thatareamenabletotheprocedure.Patientsgenerallytobeconsidered forintersphinctericresections(ISRs)arethosepatientswithStagesI–III distalrectaltumors(pretreatmentT1–T3,N0–1)within4cmoftheanal vergethatdonothaveevidenceofexternalsphincterinvolvement.The decisiontoperformarestorativeprocedureshouldbemadein conjunctionwiththepatientafterdiscussingthelikelypostoperative oncologicandperhapsmoreimportantly,functionaloutcomes.Whereas involvementoftheinternalsphincterbyaninvasivediseaseshouldnot beviewedasacontraindicationtoISR,invasionoftheexternalsphincter orthemusculatureofthepelvicfloorwouldmakethediseaseincurable viaIRP.Forthelatter,APRisrequiredforappropriateoncological resectionandoutcomes.Adigitalrectalexaminationthatshowsfixation ofthetumorshouldalsobeconsideredacontraindicationbecauseit likelymeansthatthetumorhasbrokenthroughtheintersphincteric planeandhasfixedtheinternalsphincter—anembryologicalderivative andcontinuationoftherectalwall—totheexternalsphincterorthepelvic floormusculature.SuchadiseasewouldbebettermanagedviaAPR.A preoperativepelvicMRIorendoanalultrasoundisinstrumentalin assessingtheextentoftumorspread.Indeed,anytumorthathas sphincterinvolvement,priortotheuseofneoadjuvantcombined­modalitytherapy,shouldbeexcludedfromanIRPandofferedastandard APR,despiteimprovementafterthetherapy.Tumorsthatrespondwith downstagingand/ordownsizingafterneoadjuvantchemoradiation therapygenerallymakepatientcandidatesforLAR/IRP.AchestX-ray andaCTscanoftheabdomenandpelvisshouldbeperformedtoruleout StageIVmetastaticdisease.Inthecaseoflowrectaltumors,careshould betakentoexaminethegroinsforevidenceofinguinal