HistologySq cell ca AdenocaEtiology Tobacco/alcohol Barrett’s esophagusGERD, smoking,high body massIncidence Decreasing in US Increasing in USLocation Upper to midthoracicGE junctionPrognosis Better prognosis
AJCC 7th editionAJCC 6th AJCC 7thT1 Subdivided into T1a and T1bT4 Subdivided into T4a and T4bN stage – N1 N1~3 based on number of nodes (+)M1aM1bM1a regional LNRegional LN Cervical to celiac nodesOverall stage Incorporation of tumor grade,location and histology (AD vs SQ)
• Median Jaccard conformity index was 0.69, with28% (14 of 50 investigators) achieving JCI≥0.7.• Median geographical miss index was 0.09.• Mean discordance index was 0.27.• CI was highest in middle section of volume,where tumor was bulky and more easilydefinable.
• GTV delineation by 6 radiation oncologists on10 patients using CT alone and PET-CT.
• GTV delineation by 3 radiation oncologists on28 patients using CT alone and PET-CT.
• PET-CT modified tumordelineation in 61% (17/28) incranial and/or caudaldirection.• Mean concordance indexesfor CT- and PET-CT-basedCTV/PTV were 72%/77%,vs. 72%/76%.• PET and CT may improvetarget volume definition withless geographic misses, butwithout significant effects oninter-observer variability.
• PET was able to identify most primary tumors, with asensitivity and specificity for the detection of metastaticlymph nodes of 30~93% and 79~100%.• PET-CT resulted in target volume changes.• Evidence on validity of PET-CT is very limited.– 3 studies significant positive correlation between PET-basedtumor lengths and pathological findings.– 2 studies inter- and intra-observer variability (results werenot same).– No study demonstrated improved locoregional control orsurvival by PET-CT.
From Classic to Conformal• Fundamental tenet of RT is delivery of high doseto tumor while limiting dose to normal tissues.• OAR’s and normal tissue tolerance have limiteddose to tumor.• Conformal RT:– Dose escalation to tumor while limiting dose tonormal tissues– Better local control, enhancing quality of life, andreducing Tx-associated morbidity– Need to improve accuracy of every step!
RT ProcessSteps in RT that can be represented by links in a chain.Tx accuracy will be limited by the weakest link in the chain
Can IGRT Be Solution?If you can’t see it, you can’t hit it.And if you can’t hit it, you can’t cure it.(by Harold Johns)• IGRT:– The latest imaging techniques to monitor targetvolume.– As good as accuracy only when target is known!– Improved accuracy by IGRT is limited by targetdelineation accuracy.
Target delineation: The problem!• Current practice in RT uses ICRU definition oftarget volume– Gross tumor volume (GTV)– Clinical target volume (CTV)– Planning target volume (PTV)
GTV• GTV is part of tumor that is visible with 3Dimaging.• Actual GTV delineated is dependent on imagingmodality utilized and data acquisition process.• Uncertain & variable!
GTV to CTV• Margins!– Based on assumptions from clinical or pathologicalexperience.– Subject to high degrees of uncertainty.– Making target delineation highly imprecise.• Uncertain & variable!
CTV to PTV• Margins!– Based on clinical experience– +/- suggested theoretical margins based on observedvariations.• PTV frequently includes large amount of normalhealthy tissue within high dose volume limiting total dose to PTV.• Uncertain & variable!
Importance of Target Delineation• Target contouring errors generate systematic errorswhich no level of image guidance will eliminate.• Target delineation accuracy cannot be overemphasized!
Guideline (Protocol)• Lack of continuous education and training --cause of variability in tumor delineation.• Guidelines for tumor delineation increasesagreement between observers (prostate, lung, andnasopharynx):– Average variation of GTV was reduced from 20% to13% with protocol.– Protocol included level and window settings, andtumor identification by diagnostic radiologist.
Collaboration with Diagnosticians• Development of closer links between radiologistsand oncologists to optimize interpretation ofimaging and target volume definition.• Radiologists -- to read and interpret films• Oncologists -- to treat cancer
Conclusion• Tumor delineation:– Is the weakest link in RT accuracy,– Will continue to have significant impact,– Improvement is necessary.• Possibility of converging and making tumoridentification and definition less subjective andless observer-dependent with advancement ofcomputer programming and imaging technology(MRI, PET).
Classic RT Target Volumes• Large T: bilat SCN + whole mediast + Lt gastric –’97 Mei• Middle T: bilat SCN + mediast – ’91 Teniere• Small T: bilat lower neck + SCN + upper mediast– ’89 Nishimura• Tumor bed only – ’93 Fok• Tumor bed + vertical 5~8 cm + horizontal 2 cm +no bilat SCN – ’01 Bedard
Initial Findings of Primary Tumor• Circumferential location• Tumor size• Tumor type• Depth of tumor invasion
Metastatic Lesions• Lymph node metastasis:– Naming, number and extent of LN’s– LN groups– Degree of LN (N)• NX: LN metastasis cannot be assessed• N0: No lymph node metastasis• N1: Metastasis to Group 1 LN• N2: Metastasis to Group 2 LN• N3: Metastasis to Group 3 LN• N4: Metastasis to Group 4 LN
Whenever Possible!• Gather any small piece of important information:– Clinical – P/E, EGD, EUS, CT, PET…• Evaluate operability & resectability (anatomic &physiologic staging).• Consider aggressive & multi-modal approach.• Optimize RT target volume to achieve Tx goal.• Monitor and adapt to changes during RT course.
Whenever Possible!• To go, or not to go?– 길이 아니면 가지 말라.– 질 것이 뻔한 싸움은 덤비지 말라.• Stay optimistic & affirmative if not definitely negative!– Down-staging if equivocal.– 보이는 gross tumor를 control 못하면서, 안 보이는subclinical metastasis를 너무 걱정할 필요가 없다.• If I have to go, go well!– 최악의 부작용은 local failure!– Acute & reversible side effect는 차라리 즐겨라.– Life-long complication은 무조건 피하도록.
Whenever Possible!• 어떤 경우에도 환자는 길고, 고통스러우며, 비싼 방사선치료를 받고자 하지 않는다.• In every case,– As effective as possible.– As less toxic as possible.– As simple as possible.– As short as possible.– As economic as possible.