Main Session
Sep 28
SS 12 - Sarcoma 1: From Margins to Mainstream: Advances in our Understanding of Rare Bone, Cutaneous, and Connective Tissue Tumors

171 - Sacral Chordoma: A Randomized and Observational Study on Surgery vs. Definitive Radiotherapy in Primary Localized Disease (SACRO)

04:45pm - 04:55pm PT
Room 153

Presenter(s)

Piero Fossati, MD - MedAustron Ion therapy Center, Weiner Neustadt, -1

P. Fossati1,2, A. Nachankar3,4, S. Radaelli5, E. B. Hug1, M. Stock3,6, C. Lütgendorf-Caucig1, A. Carlino3, G. Martino3, P. Mozes3, U. Mock1, M. R. Fiore7, S. Molinelli8, M. G. Petrongari9, A. Gasbarrini10, Ø. S. Bruland11, M. D. P. Sancho12, J. Hardes13, S. R. Scheipl14, B. Timmermann15, T. R. Akiyama16, V. Quagliuolo17, D. M. Donati10, L. Andreani18, J. M. Asencio19, R. Verges Capdevila20, V. Appolloni21, D. Salvatore22, S. Stacchiotti23, and A. Gronchi24; 1MedAustron Ion Therapy Center, Wiener Neustadt, Austria, 2Karl Landsteiner University of Health Sciences, Krems, Austria, 3MedAustron Ion Therapy Centre, Wiener Neustadt, Austria, 4ACMIT, Wiener Neustadt, Austria, 54Fondazione IRCCS - Istituto Nazionale dei Tumori di Milano, Milano, Italy, 6Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria, 7Fondazione CNAO - Centro Nazionale di Adroterapia Oncologica, Pavia, Italy, 8National Center of Oncological Hadrontherapy (CNAO), Pavia, Italy, 9Department of Radiation Oncology, IRCCS Regina Elena National Cancer Institute, Rome, Italy, 10IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy, 11Oslo University Hospital - Norwegian Radium Hospital, Oslo, Norway, 12Hospital Universitario Virgen del Rocío,, Sevilla, Spain, 13Klinik für Tumororthopädie - Universitätsklinikum Essen, Essen, Germany, 14Univ. Klinik für Orthopädie und Traumatologie Medizinische Universität Graz,, Pavia, Austria, 15West German Proton Therapy Centre Essen (WPE), Essen, Germany, 16Saitama Medical Center, Saitama, Japan, 17Humanitas Research Hospital, Milano, Italy, 18Universita' di Pisa - Azienda Ospedaliera Universitaria Pisana,, Pisa, Italy, 19Hospital Universitario Gregorio Marañón, Madrid, Spain, 20Hospital Val D’Hebron, Barcelona, Spain, 2118Italian Sarcoma Group ETS, Bologna, Italy, 22Fondazione IRCCS - Istituto Nazionale dei Tumori di Milano,, Milano, Italy, 23Fondazione IRCCS - Istituto Nazionale dei Tumori di Milano, Milano, Italy, 24Istituto Nazionale Tumori, Milan, Italy

Purpose/Objective(s): Definitive particle therapy of operable sacral chordoma has been proposed as a valid treatment strategy based on the good results reported by NIRS/QST in Japan. The SACRO trial 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. Patients with sacral chordoma candidate to both particle therapy and surgery are enrolled. Enrolled patients are asked to choose among 3 alternative options: surgery (+/- RT); definitive RT or randomization to either surgery (+/- RT) or definitive RT. In the trial design the two non-randomized arm will provide the pre-test probability and Bayesian statistic will be used to confirm the difference (or lack of difference) among the two arms examining the randomized arm, even if its sample size were not adequate for traditional statistical analysis. The hypothesis that this trial tries to verify is that high dose particle therapy is equivalent to en bloc surgical resection in terms of locoregional control.

Materials/Methods: Between 1st March 2017 and 1st October 2024, 170 patients were enrolled in the trial.

128 patients were eligible for evaluation (Completed treatment until November 2023 and had a Follow up of at least 1 year). No patient opted for randomization. Considering the innovative Bayesian design of the trial there is not a predetermined sample size and there is no foreseen end date. Continuous analysis is performed (every year) and results are reported when statistics is stable enough.

Results: 67 patients were treated in the radiotherapy arm and 61 patients underwent surgery. Median FU was 36 months in the surgical arm and 43 months in the RT arm. Patients were stratified according to anatomic level of tumor involvement (S1-S3 versus S4-S5). Superior lesions (S1-S3) were more frequent in the radiotherapy arm (87% S1-S3, 13% S4-S5) vs. the surgical arm (34% S1-S3, 66% S4-S5). R0 margins were achieved in 68% of the operated cases. 4 operated patients (7%) received post op RT. Among patients treated with definitive RT, 93% received carbon-ions, 7% received protons.

There was no statistically significant difference in disease-free survival among the 2 arms and this held true after stratifying for the anatomic level. 3Y-DFS was 71% for RT and 69% for surgery.

Results on OS, local recurrence, distant metastasis and QOL will be presented.

Conclusion: The trial accrual rates exceeded expectations. No patient could be enrolled to randomization. In the future even a small, randomized sample could strengthen the conclusion of the trial. Comparing the two prospective non-randomized arms there is no significant difference in recurrence and survival rates between wide en-bloc surgical resection or definitive RT with particle therapy. These data suggest non-inferiority of conservative, function-sparing, high-dose particle therapy. (ClinicalTrials.gov NCT02986516)