ESTRO 2025 - Abstract Book

S418

Clinical - Biomarkers

ESTRO 2025

Conclusion: Pre-RT SII has substantial prognostic value for TET patients undergoing adjuvant RT. Elevated SII levels may serve as a valuable biomarker, helping to identify patients who could benefit from more personalized treatment and follow up strategies.

Keywords: radiotherapy, SII, thymoma

2556

Proffered Paper A clinical and biomarker-based model to predict futile chemoradiotherapy (CRT) in patients with stage III non-small cell lung cancer (NSCLC) Rianne D.W. Vaes 1 , Francesco Cortiula 1,2 , T. Jeroen N. Hiltermann 3 , Ruud Houben 1 , Juliette Degens 4 , Lizza Hendriks 5 , Dirk De Ruysscher 1 1 Department of Radiation Oncology (Maastro Clinic), GROW Research Institute for Oncology and Reproduction, Maastricht University Medical Center+, Maastricht, Netherlands. 2 Department of Medical Oncology, University Hospital of Udine, Udine, Italy. 3 Department of Pulmonology, University of Groningen, Groningen, Netherlands. 4 Department of Pulmonary Diseases, Zuyderland Medical Center, Geleen, Netherlands. 5 Department of Pulmonary Diseases, GROW Research Institute for Oncology and Reproduction, Maastricht University Medical Center+, Maastricht, Netherlands Purpose/Objective: The current standard of care for fit patients with unresectable stage III NSCLC is concomitant CRT followed by adjuvant durvalumab. However, 20-25% of the patients treated with curative intent CRT do not survive longer than 1 year after treatment initiation, i.e. receive futile treatment. We aimed to develop a practical prognostic model that can identify patients at high risk of early mortality during and after CRT. Material/Methods: Patients with stage III NSCLC treated with curative intent CRT (platinum-doubled and chest RT, 60-66 Gy) were included in the development- (Maastro biobank, 2003-2019, NCT01084785) and validation cohorts (NCT02921854, NCT04432142). Clinical- and standard diagnostic parameters included age, gender, BMI, performance status (PS),