Rectal Cancer Contouring Guideecontour.org/training/rectal_cancer_module.pdf · – NOTE: this was created for BOTH anal and rectal cancer, which are treated quite differently, so

RectalCancerContouringGuide

eContourTeam

Youwanttocontour:RectalCancerWhatnow?

•  Findyourreferences–  RTOGcontouringatlasforanorectal:

•  h<ps://www.rtog.org/CoreLab/ContouringAtlases/Anorectal.aspx•  NOTE:thiswascreatedforBOTHanalandrectalcancer,whicharetreatedquite

differently,sopaya<enIon!•  PublicaIonvalidaIngtheaboveatlas:Myersonetal.IJROBP2009:

h<p://www.ncbi.nlm.nih.gov/pubmed/19117696–  RTOGprotocols?

•  RTOG0822actuallyshowednodifferencebetweenIMRTand3D-CRT.WhilethiscouldsIllbeareferencetoguidecontouringfor3Dblockplacementperthe3D-CRTarm,let’ssIckwiththepublishedatlas.

–  ARROContour:CAUTION!notpeer-reviewed,butaresidentpresentaIoncreatedbyARRO(ASTRO’sResidentCommi<ee)•  h<ps://www.astro.org/uploadedFiles/_MAIN_SITE/Affiliate/ARRO/Resident_Resources/

EducaIonal_Resources/ARROcase/Content_Pieces/ARROContourRectal.pdf

*eContour.orgaimstobeyourone-stopshopforcontouringguidelines,withhyperlinkstoabovehigh-yieldreferences!

LeteContour.orghelpyou!

1.  SelectCASES

2.  Fromdropdowncaselist:GIàRectalàpre-op

3.  DrawtheGTV

4.  Reviewpelvicanatomy

5.  DrawCTV

6.  Addmargin/expansiontocreatefinalPTVfortreatmentplanning

7.  BONUS:Draw“blocks”

Step1:ContourtheGTV

Grosstumor

IneContour:1.  TurncontoursOFF2.  Toggleoverlayto

MRI3.  Scrollthrough

slicestoviewextentoftumor

4.  Startyourcontourwherethetumorisobvious

ContourGTVinferiorly

ALWAYScheckyourvolumeagainstexam/colonoscopyfindingssinceimagingislesssensiIve

TogglebetweenMRIandCT

Assessmentà

MeasuredistanceGTVtoanalverge(OpIon1)

Lookinlowerlekofyourscreenforthe“Z”coordinateonlastGTVslice(-6.98cmhere).ScrolldownunIlyouseetheanalvergeandagainnotethecoordinate(-12.98cmhere).Thedifferenceis~6cm,whichwasthedistancenotedonexam(whichisbe<erthanimaging!).

MeasuredistanceGTVtoanalverge(OpIon2)

Orientyourselfin3DusingtheCROSSHAIRSin…green(coronal),blue(axial),red(sagi<al)

FromthispaIent’sAssessment,weknowthatonexamthetumorislocated6cmfromanalverge…let’sdoublecheckwhereweareatonSAGITTAL!

TIP:IntheSAGITTALview,usethemeasuringtooltochecktheverIcalextentofyourcontour.

Tryusingthemeasuringtool

NOTICE:lymphnodes!*

Enlargedperirectallymphnode

Howdoyouknowifit’salymphnodeoravessel?1.  UseMRIoverlay2.  Scrollupand

down:nodeswillberoundedstructuresthatdisappearthenreappear

3.  ContourthevesselsbeforecontouringtheGTV

*NOTE:Thesesub-cenEmeterperirectalnodesarecontouredintheGTVtoshowyoutheyareinthestandardCTV.TheseDONOTneedtobecontouredunlessgrosslyenlarged.

IneContour:1.  Turnoffall

contoursEXCEPT“Anatomy”

2.  ContoursstartwhereaortaandIVCbranch

3.  Scrollinferiorly,followingbranches

Step2:Reviewanatomyofpelvicvessels(whichwilldefinelymphnodesatrisk!)

Axialviewofvessels

CanyoufollowthesevesselsonCT?

1.  NowturnoffALLcontours

2.  Startatabdominalaorta

3.  Scrollinferiorly,followingbranches

Lymphnodessitonvessels(justcan’tseethemwhennotenlarged).ThisiswhywecontourvesselsinnodalCTV

Aorta(artery)orIVC(vein)àCommonIliacs(RandL)àInternaliliac(goposterior/infrontofsacrum)andExternalIliacs(goanterior…becomeinguinal/femoralwhenexitpelvis)

Useanatomycontours

Confirmyourfindingsbyindividuallyturningonthecontoursforeachstructure

Step3:ContouryourCTVThesearetheconsensusCTVsforanorectalcancer

Inrectalcancer,externaliliacnodes(CTVB)andinguinalnodes(CTVC)arenotatriskoftumorspread*,sowewillonlycontourCTVA

(*FYITheanalcanaldrainstotheinguinalnodes,whichiswhytheyaretreatedinanalcancer)

RTOGAnorectalcontouringatlas

Caudal(inferior)extentofCTV(MusclesandconnecIveIssueofpelvicfloorarebe<ervisualizedwithMRI)

1.  CTVshouldextendatleasttothepelvicfloor,evenifupperrectalcancer

2.  Extendtoaminimumof2cmcaudadtoGTV

PelvicfloorLevatorani

Mesorectum(peri-rectal)

CTVinlowpelvis

ScrollingthroughtheCTimages,movingsuperiorly

CTVinlowpelvis

Posteriorandlateralmargins:Extendtolateralpelvicmusclesorbone

Anteriormargin:Extendintoprostate/seminalvesiclesinamale(vaginaforfemale)

CTVinmid-pelvis

Anteriormargin:Extend1cmintoposteriorbladderwall

Mesorectum(peri-rectal)

CTVAcovers:RectumMesorectumInternaliliacvesselsPresacralspace

Prsacral

MovingsuperiorlyinCTV

Lymphnode

IncludeinternaliliacarteriesandveinsNOTICE:posteriorborderofCTVabutsexternaliliacvessels(whichwedoNOTincludeunlessT4tumorinvadingprostateorvaginalanteriorly)

Presacral

DONOTincludemuscleorbone

Cephalad(superior)extentofCTV

ConInuecontouruptowherethecommoniliacsbifurcateORL5/S1interspace*

*RadoncisamidatransiIonawayfrombonyanatomytoguidecontours(insteadcontouringsokIssue),butitsIllpervadesinmanyways–includingpelvicnodalupperborders(ieL5/S1).

Step4:AddaCTVBoostvolume

SequenIalboostmeansaddiIonaltreatmentstogivehigherdosetosmallervolume

ButhowdoIdothis??Nextslide…

ExtendCTVtocoverenIremesorectumandpresacralregionatlevelofGTV,withaminimum2cmmarginonGTVcephaladandcaudad

AddmarginforCTVBoost1.  Startwith2cmmargin

fromGTVusing“MarginforStructure”à

2.  IfenIremesorectumandpresacralareaisnotincludedinthis2cmexpansion,usebrush/pentoexpandcontour(nextslide)

3.  “Crop”contourthatextendsoutsideCTV(nextslide)

EdiIngCTVBoost

Nowwehave2problems:1.  TheenIre

mesorectumisnotincludedinourvolume–  SOLUTION:Usepen/

brushtoexpandthevolume(finalCTVBoostindarkgreen)

2.  ThecontourextendsoutsideCTV(andintobone!)–  SOLUTION(nextslide)

CurrentCTVBooststructureshowninRED

CTVBoostCTV(inclnodes)

EdiIngCTVBoost

“Crop”contourthatextendsoutsideCTVàNOTE:SomeImesyouwillwanttocropwithanaddiIonalmargin(ie0.3cmmarginPTVtoskininH&N)

Step5:AddamarginforPTV

7-10mmmarginonCTVisusuallysufficienttoaccountforpelvicmoIonCTV+7mm=PTVà

We’vedonethisbefore…

AddamarginforPTV

“Marginforstructure”

NOTE:allmarginssame

REPEATthisstepforCTVboost

Sagi<al Coronal

Alwayscheckyourfinalvolumesinsagi<alandcoronalviewstomakesureyouhavecontouredavolumethatmakessensein3dimensions!BONUS:Youcancompareyourvolumesto“bonyanatomy”blocks(nextslide)Imagesreproducedfrom:h<ps://www.astro.org/uploadedFiles/_MAIN_SITE/Affiliate/ARRO/Resident_Resources/EducaIonal_Resources/ARROcase/Content_Pieces/ARROContourRectal.pdf

FORFUN:Drawblocks/MLCs!

Youwillneedtogoto“ExternalBeamPlanning”inyourtreatmentplanningsystemeContourà“Pearls”tabdescribesbordersfor3DconformalblocksNOTE:classicbordersfora3-fieldbeamarrangementwerebasedonBONYANATOMY.WithCTsimulaIon,wecancontourareasatrisk,anddecreaseourmargins.However,fancytreatmentplanning(withIMRT)didnotimproveoutcomesonRTOG0822(whichisDIFFERENTfromanalcancer).ThemarginfromPTVto“blockedge”(meaning,theshapeofyouMLCs)issuggestedtobeabout7mmbecausethedoseattheendofthefieldis~50%(requiressomebuild-upinIssuetogetto100%prescripIondose).

References•  RTOGcontouringatlasforanorectal:

–  h<ps://www.rtog.org/CoreLab/ContouringAtlases/Anorectal.aspx–  NOTE:thiswascreatedforBOTHanalandrectalcancer,whicharetreated

quitedifferently,sopaya<enIon!–  PublicaIonvalidaIngtheaboveatlas:Myersonetal.IJROBP2009:

h<p://www.ncbi.nlm.nih.gov/pubmed/19117696•  RTOGprotocol

–  RTOG0822actuallyshowednodifferencebetweenIMRTand3D-CRT.ThiscouldsIllbeareferencetoguidecontouringandplacementof3Dblocksperthe3D-CRTarm.

–  h<ps://www.rtog.org/ClinicalTrials/ProtocolTable/StudyDetails.aspx?study=0822

•  ARROContour:CAUTION!notpeer-reviewed,butaresidentpresentaIoncreatedbyARRO(ASTRO’sResidentCommi<ee)–  h<ps://www.astro.org/uploadedFiles/_MAIN_SITE/Affiliate/ARRO/

Resident_Resources/EducaIonal_Resources/ARROcase/Content_Pieces/ARROContourRectal.pdf