ESTRO 2025 - Abstract Book

S2161

Interdisciplinary – Education in radiation oncology

ESTRO 2025

London Hospital, London, United Kingdom. 9 Department of Radiotherapy, Institute of Oncology, Ljubljana, Slovenia. 10 Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia. 11 Brachytherapy Department, Maria Sklodowska Curie National Research Institute of Oncology, Gliwice Branch, Gliwice, Poland. 12 Radiotherapy Centre, North Estonia Medical Centre Foundation, Tallinn, Estonia. 13 Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria Purpose/Objective: The Common Terminology Criteria for Adverse Events (CTCAE) is the established toxicity scoring system that assigns severity grades (G1=mild to G5=death) to Adverse Events (AEs). Compared to CTCAEv3.0 (2006) 1 , updated versions (v4.0 in 2009 and v5.0 in 2017) 2 introduced additional AE terms and changes in severity grade definitions 3 . The aim was to identify changes in severity grade definitions between AEs in v3.0 and v5.0 potentially affecting toxicity scoring for gynaecological radiotherapy. Material/Methods: After selecting AEs relevant for gynaecological radiotherapy in v3.0, changes in severity grade definitions were identified using CTCAE v3.0-to-v5.0 mapping-tables 2 . Six radiation oncologists (ROs) evaluated severity grade definitions in v5.0 for changes in: clinical interpretation (migrating the scoring to higher/lower grades), subjective (focused on patient-reported symptoms) and objective (less/more details on medication/intervention) information, and rates of severe (≥G3) events expected (less/more compared to v3.0). The analysis comprised two phases: 1) screening survey for severity grade definitions with potential relevant changes, and 2) second survey to establish consensus. Definitions where no more than two (≤2)ROs identified changes in the screening were interpreted as “No change” , while the others were included in the second survey. Consensus was based on the agreement of at least five (≥5)ROs in the second survey ( “Change” ), otherwise the conclusion was “Uncertain” (3-4ROs). Results: Gastrointestinal, urinary, reproductive, general and injury/musculoskeletal AEs (n=118) were selected (Table1). Based on the second survey (Figure1), ≥5ROs agreed on changes affecting clinical interpretation especially for G2 (31%) and G3 (30%) definitions, with Gastrointestinal, Urinary and Reproductive AEs mostly affected. In addition, 18% and 15% of G2 and G3 definitions, respectively, were judged relying more on patient-reported symptoms. However, variability in agreement was observed especially for G3 definitions, with uncertainties present for Gastrointestinal and Reproductive AEs. Less objective information was found in 51% of G3 definitions, in particular for Gastrointestinal AEs. Finally, ≥G3 rates were expected to be lower and higher using v5.0 definitions for 19% and 16% AEs, respectively, but large uncertainties in agreement were found especially in expected higher rates for Urinary AEs.