ESTRO 2025 - Abstract Book

S1434

Clinical - Lung

ESTRO 2025

Conclusion: All clinical plans and auto-plans were clinically acceptable. In this study, the plan’s quality is comparable for both techniques but auto-plans show slightly better plan quality and consistency. These results demonstrate the promising potential of auto-planning in generating consistent, high-quality plans while eliminating potential inter planner variability.

Keywords: SBRT, autoplannig

References: 1. Kubo et al. Inter-planner variation in treatment-plan quality of plan created with knowledge-based treatment planning system. Physica Medica 67 (2019) 132-140

4269

Digital Poster High dose reirradiation for intrathoracic relapse of lung cancer: a retrospective experience. Eugenio Cammareri 1,2 , Stefania Volpe 1,2 , Denis Nicolò 1,2 , Marco Romelli 3 , Gaia Piperno 1 , Maria Alessia Zerella 1 , Cristiana Fodor 1 , Federica Cattani 4 , Joost J. Nuyttens 5 , Roberto Orecchia 6 , Barbara Alicja Jereczek-Fossa 1,2 1 Division of Radiation Oncology, IEO European Institute of Oncology IRCCS, Milan, Italy. 2 Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy. 3 Molecular and Pharmaco-Epidemiology Unit, Department of Experimental Oncology, IEO European Institute of Oncology IRCCS, Milan, Italy. 4 Medical Physics Unit, IEO European Institute of Oncology IRCCS, Milan, Italy. 5 Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, Netherlands. 6 Scientific Direction, IEO European Institute of Oncology IRCCS, Milan, Italy Purpose/Objective: Locoregional failures after radiotherapy (RT) for primary lung cancer account for 30% of relapses. Retrospective studies have shown poor survival outcomes and even some lethal toxicities due to the increased risk of a second course of RT in the thoracic region, a delicate area with many vital organs at risk. However, recent monocentric retrospective studies, aided by innovations in RT, have shown promising outcomes for patients with isolated locoregional recurrence after initial RT. Material/Methods: In this monocentric study, we included patients with recurrent lung cancer in the thorax after RT (defined as relapse or a new tumor within 5 cm of the 50 Gy EQD2,10 isodose line of previous RT), treated with conventionally fractionated RT (CFRT) or stereotactic body RT (SBRT), with a re-irradiation dose of ≥ 45 Gy EQD2,10. The minimum interval between the first and second courses of RT was required to be ≥9 months. Results: From 2011 to 2023, a total of 44 patients were included in this study. The median time to relapse after initial RT was 19.3 months (IQR 11.4 – 36.6 months). The median prescribed dose of the first RT was 83.3Gy EQD2,10 (IQR 60 – 126Gy EQD2,10). For reirradiation, 36 patients were treated with SBRT and 8 with CFRT, with a median dose of 66Gy EQD2,10 (IQR 60 – 85.9Gy EQD2,10). According to the ESTRO consensus on re-irradiation, 22 patients (50%) had a geometric overlap of the irradiated volumes (type 1). For additional patient, tumor, and treatment characteristics, see Table 1