ESTRO 36 Abstract Book

S367 ESTRO 36 _______________________________________________________________________________________________

gastric LNS [R: 3, C: 0] and paraaortic LNS [R: 3, C: 1]; for proximal EHC - paraaortic LNS [R: 3, C: 1]; for middle EHC - paraaortic LNS [R: 3, C: 1] and superior mesenteric artery (SMA) LNS [R: 2, C: 0]; for distal EHC - paraaortic LNS [R: 3, C: 1], SMA LNS [R: 4, C: 1] and anterior pancreatico- duodenal LNS [R: 3, C: 1]; for GBC - paraaortic LNS [R: 4, C: 1] and SMA LNS [R: 2, C: 1]. Nodal areas that seem to be unnecessarily irradiated include celiac lymph nodes for middle and distal EHC [R: 0, C: 3]. Moreover, the interaorto-caval LNS seems to be the only subsite of the paraaortic LNS that should be included into CTV, which can limit the increase of overall treatment volume caused by inclusion of paraaortic LNS. Similarly, only the posterior group of pancreatico-duodenal LNS should be included into CTV, except for distal EHC - where both posterior and anterior pancreatico-duodenal LNS are at high risk of involvement. Conclusion This is the first study that reports on the nodal areas of potential geographical misses and the unnecessarily irradiated nodal areas in adjuvant RT for BTC. Paraaortic LNS are at very high risk of involvement in all BTC locations - but are almost uniformly omitted, as well as the SMA LNS for middle and distal EHC. Contrarily, celiac LNS are always included into CTV, which seems unnecessary for distal and middle EHC, at least in less advanced stages. In view of some considerable discrepancies between pathological-surgical data and the elective nodal CTVs used in common practice, there is an obvious need for the international consensus guidelines. PO-0702 Phase I trial evaluating panitumumab in combination with chemoradiotherapy for anal cancers V. Vendrely 1 , C. Lemanski 2 , E. Le Prise 3 , E. Maillard 4 , X. Mirabel 5 , G. Lledo 6 , L. Dahan 7 , A. Adenis 5 , G. Paintaud 8 , T. Lecomte 9 , C. Levy-Piedbois 10 , E. Terrebonne 1 , V. Mammar 6 , S. Manfredi 11 , T. Aparicio 12 1 CHU de Bordeaux, Gironde, Pessac, France 2 Institut Regional du Cancer Montpellier, Herault, Montpellier, France 3 Centre Eugene Marquis, Ille-et-Villaine, Rennes, France 4 Federation Francophone de Cancerologie Digestive, Cote-d'Or, Dijon, France 5 Centre Oscar Lambret, Nord, Lille, France 6 Hopital prive Jean Mermoz, Rhone, Lyon, France 7 CHU La Timone, Bouches-du-Rhone, Marseille, France 8 CHU Bretonneau, Indre-et-Loire, Tours, France 9 CHU Trousseau, Indre-et-Loire, Tours, France 10 Institut de Radiotherapie, Seine-Saint-Denis, Bobigny, France 11 EPICAD INSERM U866- Universite de Bourgogne Franche Comte, Cotes-d'Or, Dijon, France 12 CHU APHP- Hopital Avicenne, Seine-Saint-Denis, Bobigny, France Purpose or Objective To assess the safety and determine the recommended Phase II dose of anti-EGFR Panitumumab combined with Mitomycin, 5FU and radiotherapy in patients (pts) with locally advanced epidermoid anal cancers. Material and Methods This open prospective, multicentric, single-arm phase I study included patients (OMS: 0 or 1) with histologically proven epidermoid anal cancers T2> 3 cm, T3, T4 or every T-N+, M0. Phase I study was done to determine the Dose Limiting Toxicity (DLT) and the Maximum Tolerated Dose (MTD) of chemotherapy with a conventional 3+3 design. Radiotherapy (conformational 3D or IMRT) was delivered over 5 weeks at 1.8 Gy/fraction to reach a total dose of 45 Gy to the pelvis. After a 2 week break a boost of 20 Gy/2 Gy was delivered to the tumor. Mitomycin was administered on day 1, 29 and 50 at 10 mg/m², 5FU on Poster: Clinical track: Lower GI (colon, rectum, anus)

Conclusion A spectacular reduction in mean heart dose of 8,2Gy can be obtained by deep inspiration breath-hold, with similar or even lower mean lung dose, compared to the current standard partial VMAT/IMRT. This may decrease the risk of radiation induced cardiac toxicity. PO-0701 Discrepancies between pathologi cal data on nodal spread and the CTVs in RT for biliary tract cancer J. Socha 1 , M. Michalak 2 , G. Wołąkiewicz 3 , L. Kępka 3 1 Regional Oncology Centre Czêstochowa, Radiotherapy, Czestochowa, Poland 2 Independent Public Care Facility of the Ministry of the Interior and Warmian & Mazurian Oncology Center, Diagnostic imaging, Olsztyn, Poland 3 Independent Public Care Facility of the Ministry of the Interior and Warmian & Mazurian Oncology Center, Radiation Oncology, Olsztyn, Poland Purpose or Objective To compare pathological-surgical data on the pattern of nodal spread in biliary tract cancer (BTC) with nodal CTVs commonly used in adjuvant radiotherapy (RT) for BTC. Material and Methods A comprehensive literature search was performed, using the ‘‘PubMed’’ and ‘‘Google Scholar’’ databases, to select articles on adjuvant RT for BTC, that provided information on the lymph node stations (LNS) included into CTV. Another search was done to extract the surgical and pathological data on the patterns of nodal recurrence and lymph node involvement in BTC. The risk of nodal involvement and the degree of concordance between different RT studies on including each of the LNS into CTV were established with numerical scales presented in Table 1, and compared to show the nodal areas of potential geographical misses as well as unnecessarily irradiated nodal areas, separately for intrahepatic cholangiocarcinoma (IHC), extrahepatic cholangiocarcinoma (EHC) and gall bladder cancer (GBC). Results Out of 59 studies on the use of adjuvant RT in BTC, 19 were finally included: 1 prospective, 15 retrospective and 3 reviews; 14 pathological and/or surgical studies that reported on the lymph node positivity rates in BTC were included. Nodal areas of potential geographical misses include: for right IHC - paraaortic LNS [risk level (R): 3, degree of concordance (C): 1]; for left or hilar IHC - left