ESTRO 2025 - Abstract Book

S1337

Clinical - Lung

ESTRO 2025

and Theranostics, Paracelsus Medical University, SALK, Salzburg, Austria. 4 Nuclear Medicine, Paracelsus Medical University, SALK, Salzburg, Austria. 5 Institute of Pathology, Paracelsus Medical University, SALK, Salzburg, Austria. 6 RadART - Institute for Research and Development on Advanced Radiation Technologies, Paracelsus Medical University, SALK, Salzburg, Austria Purpose/Objective: Stratification based on specific image biomarkers applicable in the clinical setting could help optimize treatment outcomes for recurrent non-small cell lung cancer patients. For this purpose, we aimed to determine the impact of positive delta changes (any difference above zero >0) between baseline 18F-FDG PET/CT metrics at first and reirradiation on clinical outcomes in NSCLC patients who underwent high-dose thoracic reirradiation chemoimmunotherapy. Material/Methods: Forty-seven patients who underwent ablative thoracic reirradiation at our institute between 2013 and 2021 met the inclusion criteria. All patients had histologically verified non-small cell lung cancer, were with an ECOG (Eastern Cooperative Oncology Group) ≤ 2 and underwent 18F-FDG-PET/CT for diagnostic purposes, both at initiall diagnosis and at recurrence. Quantitative metabolic volume and intensity parameters were measured before first irradiation and before reirradiation, and the difference above zero (>0; delta change) between them was statistically correlated to LRC, PFS, and OS. The time interval between radiation treatments was at least nine months. Results: Patients were followed for a median time of 17.7 months. The median overall survival (OS) was 21.8 months (95%- CI: 16.3-27.3), the median progression-free survival (PFS) was 12 months (95%-CI: 6.7-17.3), and the median locoregional control (LRC) was 13 months (95%-CI: 9.0-17.0). The multivariate analysis revealed that the delta changes of SULpeak and SUVmax of the lymph nodes significantly impacted OS (SUL peak p=0.017; SUV max p=0.006), PFS (SULpeak p=0.010; SUVmax p=0.009) and LRC (SULpeak p < 0.001; SUVmax p=0.003). Conclusion: Delta changes of SULpeak and SUVmax of the lymph nodes significantly impacted all clinical endpoints (OS, PFS and LRC) in recurrent NSCLC patients treated with reirradiation-chemoimmunotherapy.

Keywords: reirradiation, NSCLC, image biomarkers

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Digital Poster TIME TO NEXT TREATMENT FOLLOWING SUB-ABLATIVE PROGRESSION DIRECTED RADIATION THERAPY FOR OLIGOPROGRESSIVE NON-SMALL-CELL LUNG CANCER Riccardo Ray Colciago 1 , Chiara Chissotti 1,2 , Federica Ferrario 1,2 , Maria Belmonte 1,2 , Giorgio Purrello 1,2 , Valeria Faccenda 3 , Denis Panizza 3 , Stefania Canova 4 , Gaia Passarella 4 , Diego Luigi Cortinovis 4 , Stefano Arcangeli 1,2 1 Medicine and Surgery Department, University of Milan Bicocca, Milan, Italy. 2 Radiation Oncology Unit, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy. 3 Medical Physiscs Unit, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy. 4 Medical Oncolgy Unit, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy Purpose/Objective: We aimed to evaluate whether progression directed radiation therapy (PDRT) can prolong the initiation of a subsequent therapy regimen in a cohort of patients with oligoprogressive NSCLC.

Material/Methods: A retrospective analysis was conducted on NSCLC patients undergoing PDRT for extra-cranial oligoprogressive