ESTRO 2025 - Abstract Book

S837

Clinical - Gynaecology

ESTRO 2025

2638

Proffered Paper EMBRACE II - a multicenter prospective interventional cohort study on IGRT-IMRT+cisplatin+MR-IGABT in locally advanced cervix cancer: overall results Richard Pötter 1 , Kari Tanderup 2 , Maximilian Paul Schmid 1 , Stefan Ecker 1 , Petra Kroon 3 , Jacob Lindegaard 4 , Kjersti Bruheim 5 , Barbara Segedin 6 , Alina Sturdza 1 , Henrike Westerveld 7 , Supriya Chopra 8 , Fleur Huang 9 , Margit Valgma 10 , Laura Velema 11 , Astrid de Leeuw 3 , Max Peters 3 , Marianne Sanggaard Assenholt 4 , Nicole Eder-Nesvacil 1 , Johannes Knoth 1 , Monica Serban 12 , Sofia Spampinato 13 , Kathrin Kirchheiner 1 , Remi Nout 13 , Ina Jürgenliemk-Schulz 3 , Christian Kirisits 1 1 Department of Radiation Oncology, Medical University of Vienna, General Hospital of Vienna, Comprehensive Cancer Center, Vienna, Austria. 2 Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark. 3 Department of Radiation Oncology, University Medical Centre Utrecht, Utrecht, Netherlands. 4 Department of Oncology, Aarhus University Hospital, Aarhus, Denmark. 5 Department of Oncology, Oslo University Hospital, Oslo, Norway. 6 Department of Radiotherapy, Institute of Oncology, Ljubljana, Slovenia. 7 Department of Radiation Oncology, Amsterdam UMC, Location of University of Amsterdam, Amterdam, Netherlands. 8 Department of Radiation Oncology and Medical Physics, Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre, Homi Bhabha National Institute, Navi Mumbai, India. 9 Department of Oncology, Cross Cancer Institute and University of Alberta, Edmonton, Canada. 10 Radiotherapy Centre, North Estonia Medical Centre Foundation, Tallinn, Estonia. 11 Department of Radiation Oncology, Leiden University Medical Center, Leiden, Netherlands. 12 Department of Oncology, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Canada. 13 Department of Radiotherapy, Erasmus MC Cancer Institute, University Medical Center Rotterdam, Rotterdam, Netherlands Purpose/Objective: To present mature overall clinical results from the first prospective interventional multicentre EMBRACE-II study in Locally Advanced Cervical Cancer (LACC) (NCT03617133) investigating – multiple hypotheses driven - advanced TNM 2013 -based staging (clin-MRI-PET-CT), adaptive target-definition, highly conformal multi-parametric treatment planning (minimal margins, multiple dose-constraints) and Image-Guided delivery (IGRT-IMRT, Lymph-Node Simultaneous-Integrated-boost (LN-SIB), Para-aortic-Radiotherapy (PAO-RT), ≥5xcisplatin, MR-Image-Guided Adaptive Brachytherapy (MR-IGABT)). Material/Methods: Data from 1482 patients with LACC stage T1-4N0/1M1 PAO/ING (clin-MRI-PETCT) treated in 49 centres were prospectively collected (2016-2021). Treatment comprised IGRT-IMRT-VMAT, concurrent cisplatin and MR-IGABT. Various targets, OARs and dose-constraints were prescribed (ICRU-89, EMBRACE-I 1,2,3 ). Elective EBRT-dose was 45Gy (1.8Gy/fraction), LN-SIB 55-57.5Gy (coverage-probability-planning), dose to adaptive CTV-T HR D 90% ≥90Gy. Elective EBRT-target volumes (small pelvis; large pelvis (LP) including aortic bifurcation; LP+PAO-RT) were selected based on LN-parameters (>2LN, common-iliac LN). IGRT-IMRT was with 5 mm PTV-margins. IC-IS brachytherapy was enforced. A comprehensive accreditation and QA-programme was applied. Actuarial Kaplan-Meier estimates for first recurrence/vital status were calculated (data at 06112024) for the overall cohort and for two sub-cohorts for various clinical endpoints (Table-Figure). Morbidity was prospectively assessed (CTCAEv3.0-4.0). Results: Median follow-up (time to event/vital status) was 39/46 months for 1376 patients investigated. Median age was 51, WHO-Performance-Score 0/1 68/30%. TNM 2013 stage was T1b1+2 13.5%, T2a1+2 5.4%, T2b 66%, T3a 1.4%, T3b 11%, T4 2.5%, N1 50%, M1 PAO 8.6%. 83% had squamous-cell carcinoma, 15% adeno-carcinoma. Median GTV-T init was 37cm 3 (19,67 (IQR)). Mean elective EBRT-dose was 45Gy (±0.5), LN-SIB 57Gy. 97% received cisplatin, 74% ≥5cycles. Elective target was LP/LP+PAO in 66/27%; median PTV 43Gy 1409/1758cm 3 ; conformity-index 1.03/1.05; PTV-N-SIB per patient 38cm 3 . IGABT was IC-IS in 74%, HDR in 70%. Median overall-treatment- time was 43 days (40,46). Median GTV-T res was 5cm 3