ESTRO 2023 - Abstract Book

S18

Saturday 13 May

ESTRO 2023

4 University of Tübingen, Women’s Health, Tübingen, Germany; 5 University of Tübingen, Pathology, Tübingen, Germany; 6 Institute Verbeeten, Radiation Oncology, Tilburg, The Netherlands; 7 Netherlands Cancer Institute, Radiation Oncology, Amsterdam, The Netherlands; 8 Amsterdam University Medical Centers, Radiation Oncology, Amsterdam, The Netherlands; 9 Radiotherapy Institute Friesland, Radiation Oncology, Leeuwarden, The Netherlands; 10 First Faculty of Medicine, Charles University and General University Hospital, Obstetrics and Gynaecology, Prague, Czech Republic; 11 First Faculty of Medicine, Charles University and General University Hospital, Institute of Pathology, Prague, Czech Republic; 12 Catharina Hospital, Radiation Oncology, Eindhoven, The Netherlands; 13 Erasmus MC – Cancer Institute, Radiation Oncology, Rotterdam, The Netherlands; 14 Institut Gustave Roussy, Radiation Oncology, Villejuif, France; 15 Institut Gustave Roussy, Pathology, Villejuif, France; 16 University Medical Center Groningen, Radiation Oncology, Groningen, The Netherlands; 17 St. Luke’s Hospital, Radiation Oncology, Dublin, Ireland; 18 Trinity St James’s Cancer Institute, St. James’s Hospital, Histopathology, Dublin, Ireland; 19 Haaglanden Medical Center, Radiation Oncology, The Hague, The Netherlands; 20 University Medical Center Utrecht, Radiation Oncology, Utrecht, The Netherlands; 21 Rotkreuzklinikum München, Women’s Health, München, The Netherlands; 22 Leiden University Medical Center, Pathology, Leiden, The Netherlands Purpose or Objective The PORTEC-4a trial is the first study worldwide that introduced molecular factors in decision making on adjuvant treatment for women with high-intermediate risk endometrial cancer (HIR-EC). For patients randomised to the intervention arm, adjuvant treatment was based upon a molecular-integrated risk profile. Here we report on the feasibility of determining the molecular-integrated risk profile and starting adjuvant therapy within a clinically acceptable time frame after surgery. Materials and Methods Women with complete surgical resection of HIR-EC were eligible. Patients were randomized (2:1) between individualized treatment based upon the molecular-integrated risk profile and standard vaginal brachytherapy (VBT). In patients with a favourable profile, adjuvant treatment was omitted; in those with an intermediate profile, VBT was recommended, and the small group with an unfavourable profile received pelvic radiotherapy. After randomisation, histopathological slides and representative tumour block were obtained by pathology laboratories which had been validated for review and determination of the molecular-integrated risk profile. Histopathological, immunohistochemical and molecular analyses were performed, after which risk groups assignment was done and adjuvant therapy could be initiated, figure 1. Accrual completed in December 2021 and final results are expected in 2024.

Results Between 2016 and 2021, 569 patients were enrolled of whom 361 evaluable patients were allocated to the intervention arm. Twelve pathology laboratories in 8 European countries were validated during the conducted of the trial. Of 284 patients the molecular-integrated risk profile was determined at the LUMC department of Pathology and 77 at laboratories elsewhere. Average time between randomisation and result of the risk profile was 2 weeks (range 0 – 6 weeks) for LUMC and 3 weeks (0 – 12 weeks) for other laboratories. For 48.5% of participants pathology review took longer than 2 weeks, of which 1.1% more than 6 weeks. Median time between surgery and start of adjuvant treatment was 7 weeks (0 – 13 weeks); this was 7 weeks (5 – 12 weeks) for patients receiving VBT and 8 weeks (5 – 13 weeks) for pelvic radiotherapy. Less than 10% of patients started adjuvant treatment more than 9 weeks after surgery. Only in 2 (0.5%) cases determination of the risk profile failed due to technical issues; these patients received VBT according to protocol. Conclusion Determination of the molecular-integrated risk profile for participants of the PORTEC-4a trial was proven to be feasible within a clinically acceptable time frame. It is shown that prompt sending of the tumour material, excellent collaboration between clinicians, pathologists within and between centers is essential to ensure timely results and treatment. Development of quicker and cheaper DNA-sequencing methods might greatly facilitate implementation of the molecular- integrated risk profile in routine clinical practice. MO-0051 SBRT in oligometastatic uterine cancer: a large, multicenter, retrospective study. G. Macchia 1 , D. Pezzulla 1 , M. Campitelli 2 , C. Laliscia 3 , A. Fodor 4 , P. Bonome 1 , L. Draghini 5 , E. Ippolito 6 , V. De Sanctis 7 , M. Ferioli 8 , F. Titone 9 , V. Balcet 10 , V. Di Cataldo 11 , D. Russo 12 , L. Vicenzi 13 , S. Cossa 14 , S. Lucci 2 , F. Deodato 1,15 , M.A. Gambacorta 2,16 , G. Ferrandina 17 1 Gemelli Molise Hospital – Università Cattolica del Sacro Cuore, Radiation Oncology Unit, Campobasso, Italy; 2 Fondazione Policlinico Universitario Agostino Gemelli IRCCS, UOC di Radioterapia, Dipartimento di Scienze Radiologiche, Radioterapiche ed Ematologiche, Roma, Italy; 3 University of Pisa, Department of Translational Medicine, Division of Radiation Oncology, Pisa, Italy; 4 IRCCS San Raffaele Scientific Institute, Department of Radiation Oncology, Milano, Italy; 5 S Maria Hospital, Radiation Oncology Center, Terni, Italy; 6 Campus Bio-Medico University, Department of Radiation Oncology, Roma, Italy; 7 Sapienza University of Rome, S. Andrea Hospital, 7Radiotherapy Oncology, Department