ESTRO 2021 Abstract Book

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ESTRO 2021

1035-1039, 00189, Department of Radiation Oncology, Rome, Italy; 4 Ecomedica, Ecomedica Radioterapia, Empoli, Italy; 5 European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132, Division of Radiation Oncology, IEO, Milan, Italy; 6 Azienda Ospedaliera Universitaria Careggi, University of Florence, Radiation Oncology Unit, Florence, Italy; 7 IRCCS San Raffaele Scientific Institute, Department of Radiation Oncology, Milan, Italy; 8 Campus Bio-Medico University, Via A. del Portillo, 21, 00128, Radiation Oncology, Rome, Italy; 9 Pisa University Hospital, Via Roma 67, 56123, Radiation Oncology Unit, Pisa, Italy; 10 Divisione di Radioterapia Oncologica - Gemelli ART, Fondazione Policlinico Universitario A.Gemelli IRCCS, Rome, Italy; 11 Azienda Ospedaliera S. Gerardo, Department of Radiation Oncology, Monza, Italy; 12 University Hospital of Modena, Radiation Therapy Unit, Modena, Italy; 13 ASST Spedali Civili di Brescia - Brescia University, Radiation Oncology Department, Brescia, Italy; 14 S. Maria Hospital, Radiation Oncology Centre, Terni, Italy; 15 Humanitas Gavazzeni, 24125, Department of Radiation Oncology, Bergamo, Italy; 16 University Hospital "Jean Minjoz", Department of Radiation Oncology, Besançon, France; 17 University of Lausanne (UniL), Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland; 18 Veneto Institute of Oncology IOV-IRCCS, Radiation Oncology Unit, Padua, Italy; 19 Casa di Cura Macchiarella, Radiotherapy Unit, Palermo, Italy; 20 ARNAS Ospedale Civico, Department of Radiation Oncology, Palermo, Italy; 21 Fondazione IRCCS Istituto Nazionale dei Tumori, Department of Radiation Oncology 1, Milan, Italy; 22 ULSS5, Radiotherapy Unit, Rovigo, Italy; 23 Marrelli Hospital, Radiotherapy Marrelli Hospital, Crotone, Italy; 24 Fondazione Policlinico Universitario A.Gemelli IRCCS, Divisione di Radioterapia Oncologica - Gemelli ART, Rome, Rome, Italy; 25 Università Cattolica del Sacro Cuore, -, Rome, Italy; 26 Vita-Salute San Raffaele University, -, Milan, Italy; 27 IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132, Division of Radiation Oncology, Milan, Italy; 28 University of Milan, Via Festa del Perdono, 7, 20122 , Department of Oncology and Hemato-oncology, Milan, Italy; 29 University of Brescia, -, Brescia, Italy Purpose or Objective stereotactic ablative radiotherapy (SABR) has been shown to increase survival rates in oligometastatic disease (OMD), but local control of colorectal metastases still remains poor. We aimed to identify potential predictive factors of SABR response through a multicenter large retrospective database and to investigate how lung SABR can impact on the progression to the polymetastatic disease. Materials and Methods the study involved 22 centers, and was approved by the Ethical Committee (Prot. Negrar 2019-ZT). 1023 lung metastases treated with SABR in 622 patients were reported. The median biological equivalent dose (BED) was 105 Gy 10 . Lesion diameter GTV, PTV volume, dose, fractionations, and site of primary tumor were evaluated as potential predictive marker for SABR response for the primary end-point local progression-free survival (LPFS). EGFR, KRAS, NRAS, BRAF, and MSI were also evaluated. Secondary end-point was the time to the polymetastatic conversion (ttPMC). Results the median follow-up was 26 months (range 3-117 months). The median lesion diameter was 13 mm (range 4- 58 mm). The 2- and 3-year LPFS were 75.6% and 71%, respectively. At the univariate analysis, BED ≥125Gy 10 was associated with improved LPFS (2-year: 94.1% versus 72.6%; p= <0.0001), single fraction SABR correlated with better LPFS in the overall population (2-year: 80.6% versus 73.7%; p=0.03), but no significant difference was observed when considering the population treated with BED>100 Gy 10 . Lesion diameter ≤19 mm correlated with improved LPFS (2-year 80% versus 60%; p=<0.0001). The median ttPMC was 26 months, and the 2-year ttPMC was 54.5%. The median PFS was 11.3 months. After SABR, 36% patients had polymetastatic relapse, 39.5% patients had further oligometastatic relapse, and 24.5% patients had no relapse at all. Conclusion The present is the largest series of lung colorectal metastases treated with SABR. The results support the use of SBRT in lung oligometastatic colorectal cancer patients as it might delay the transition to polymetastatic disease or offer relatively long disease-free period in selected cases. Several biological and clinical predictive factors were identified to assure the highest local control, on the basis of which a decisional algorithm will be derived. PH-0113 Anti-Epidermal Growth Factor Receptor Therapy in combination with Chemoradiotherapy for the Treatment of Locally Advanced Anal Canal Carcinoma: Results of a Phase II Study with Panitumumab (FFCD 0904) V. Vendrely 1 , P. Ronchin 2 , K. Le-Malicot 3 , M. MINSAT 4 , C. Lemanski 5 , X. MIRABEL 6 , A. LIEVRE 7 , A. DARUT- JOUVE 8 , C. DE LA Fouchardiere 9 , G. Breysacher 10 , D. Argo-Leignel 11 , E. Thimonier 12 , N. Magne 13 , C. Belletier 14 , C. Lepage 15 , T. Aparicio 16 1 Universitary Hospital, Radiation Oncology, Bordeaux, France; 2 CENTRE AZUREEN DE CANCEROLOGIE, Radiation Oncology, Mougins, France; 3 university Of Burgundy, 3federation Francophone De Cancerologie Digestive (Ffcd), Epicad Inserm Lnc-Umr 1231, Dijon, France; 4 institut Curie, Radiation Oncology, Paris, France; 5 institut Regional Du Cancer Montpellier, Radiation Oncology, Montpellier, France; 6 centre Oscar Lambret, Radiation Oncology, Lille, France; 7 chu De Pontchaillou, Gastroenterology, Rennes, France; 8 institut De Cancérologie De Bourgogne Grrecc, Medical Oncology, Dijon, France; 9 leon Berard, Medical Oncology, Lyon, France; 10 hopitaux Civils De Colmar, Gastroenterology, Colmar, France; 11 chbs - Hopital Du Scorff, Radiotherapy And Oncology, Lorient, France; 12 annecy Genevois, Radiotherapy, Pringy, France; 13 14institut De Cancérologie Lucien Neuwirth, Radiotherapy And Oncology, Saint Priest En Jarez, France; 14 centre Paul Strauss, Oncology, Strasbourg, France; 15 centre Hospitalier Universitaire De Dijon, Epicad Inserm Lnc-Umr 1231, University Of Burgundy, Hepato-Gastroenterology And Digestive Oncology, Dijon, France; 16 hopital Saint Louis, Gastroenterology And Digestive Oncology , Paris, France Purpose or Objective Standard treatment of anal squamous cell carcinoma is 5-fluorouracil (5FU) and mitomycin C (MMC) based chemoradiotherapy (CRT). This phase II study (EudraCT: 2011-005436-26) studied the tolerance and complete response (CR) rate at 8 weeks of panitumumab (Pmab) combined with MMC-5FU based CRT.