ESTRO 2025 - Abstract Book

S4423

Late-breaking abstracts

ESTRO 2025

Conclusion PORTEC-4a trial was first to incorporate a molecular-integrated classification into decisions for adjuvant therapy in EC. Individualised treatment was shown to achieve similar high local control, while sparing almost half of the patients adjuvant treatment, and suggesting better locoregional control with EBRT for those with unfavourable profile.

Keywords: Endometrial Cancer, Molecular-tailored treatment

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Proffered Paper SACRAL CHORDOMA: A RANDOMIZED & OBSERVATIONAL STUDY ON SURGERY VS DEFINITIVE PARTICLE BASED RADIOTHERAPY IN PRIMARY LOCALIZED DISEASE (SACRO) Piero Fossati 1,2 , Stefano Radaelli 3 , Ankita Nachankar 1,4 , Eugen Boris Hug 1 , Markus Stock 5,2 , Carola Lütgendorf Caucig 1 , Maria Rosaria Fiore 6 , Silvia Molinelli 7 , Alessandro Gasbarrini 8 , Maria Grazia Petrongari 9 , Øyvind Sverre Bruland 10 , Maria Pilar Sancho 11 , Jendrik Hardes 12 , Susanne Scheipl 13 , Beate Timmermann 14 , Toru Akiyama 15 , Vittorio Quagliuolo 16 , Davide Maria Donati 17 , Lorenzo Andreani 18 , Jose Manuel Asencio 19 , Ramona Verges Capdevilla 20 , Gloria Marquina Ospina 21 , Viviana Appolloni 22 , Silvia Stacchiotti 23 , Alessandro Gronchi 3 1 Radiation Oncology, MedAustron Ion Therapy Centre, Wiener Neustadt, Austria. 2 Molecular Oncology an Hematology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria. 3 Surgery, IRCCS - Istituto Nazionale Tumori Regina Elena, Milano, Italy. 4 ACMIT, ACMIT, Wiener Neustadt, Austria. 5 Medical Physics, MedAustron Ion Therapy Centre, Wiener Neustadt, Austria. 6 Radiation oncology, Fondazione CNAO - Centro Nazionale di Adroterapia Oncologica, Pavia, Italy. 7 Medical Physics, Fondazione CNAO - Centro Nazionale di Adroterapia Oncologica, Pavia, Italy. 8 Vertebral Surgery, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy. 9 Radiation oncology, IRCCS - Istituto Nazionale Tumori Regina Elena, Roma, Italy. 10 Department of Medical Oncology & Radiotherap, Oslo University Hospital - Norwegian Radium Hospital, Oslo, Norway. 11 Medical Oncology and Radiotherapy, Hospital Universitario Virgen del Rocío, Sevilla, Spain. 12 Klinik für Tumororthopädie, Universitätsklinikum Essen, Essen, Germany. 13 Univ. Klinik für Orthopädie und Traumatologie, Medizinische Universität Graz, Graz, Austria. 14 Radiation Oncology, Westdeutsches Protonentherapiezentrum Essen (WPE),, Essen, Germany. 15 Orthopedic surgery, Saitama Medical Center, Saitama, Japan. 16 Oncological surgery, Humanitas Research Hospital, Milano, Italy. 17 Orthopedic Oncology, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy. 18 Orthopedics and Trauma Surgery, Universita' di Pisa - Azienda Ospedaliera Universitaria Pisana, Pisa, Italy. 19 General surgery, Hospital Universitario Gregorio Marañón, Madrid, Spain. 20 Radiation Oncology, Hospital Val D’Hebron, Barcelona, Spain. 21 Medical Oncology, Hospital San Carlo, Madrid, Spain. 22 Italian Sarcoma Group ETS, Italian Sarcoma Group ETS, Bologna, Italy. 23 Medical Oncology, IRCCS - Istituto Nazionale Tumori Regina Elena, Milano, Italy Purpose/Objective Definitive particle therapy of operable sacral chordoma has been proposed as a valid treatment strategy based on the good results reported by NIRS/QST [1]. The SACRO trial (ClinicalTrials.gov NCT02986516) is an international Bayesian prospective randomized/observational clinical study comparing surgery vs. definitive particle therapy and focusing on disease-free survival as primary endpoint and OS, toxicity and QOL as secondary endpoints. The trial is sponsored by the Italian Sarcoma Group. Enrolled patients are asked to choose among 3 alternative options: surgery (+/- RT); definitive RT, or randomization to either surgery (+/- RT) or definitive RT. Material/Methods Between 1 st March 2017 and 1 st October 2024, 170 patients were enrolled in the trial. 153 patients were eligible for the fourth interim analysis (in 17 the CRF was not yet complete). No patient opted for randomization. Results 84 patients were treated in the radiotherapy arm and 69 patients underwent surgery. Patients were stratified according to anatomic level of tumor involvement (S1-S3 versus S4-S5). Superior lesions (S1-S3) were more