S765
Clinical - Lung
ESTRO 2026
References: 1. Gomez DR, Blumenschein GR Jr, Lee JJ, et al. Local consolidative therapy versus maintenance therapy or observation for patients with oligometastatic non small cell lung cancer without progression after first line systemic therapy: a multicentre, randomised, controlled, phase 2 study.*Lancet Oncol.* 20162. Gomez DR, Tang C, Zhang J, et al. Local consolidative therapy vs. maintenance therapy orobservation for patients with oligometastatic non small cell lung cancer: Long term results of a multi-institutional, phase II, randomized study. *J Clin Oncol.* 20193. Iyengar P, Wardak Z, Gerber DE, et al. Consolidative radiotherapy for limited metastatic non small cell lung cancer: A phase 2 randomized clinical trial. *JAMA Oncol.*2018. Keywords: CROM IN CA LUNG Digital Poster 850 Patterns of practice in thoracic reirradiation in Ontario: a department-level survey Geraldine A Murphy 1 , Brian Liszewski 2 , Nareesa Ishmail 2 , Eric Gutierrez 2 , Timothy P Hanna 2,3 , Jason Pantarotto 2,4 , Jean-Pierre Bissonnette 1,2 , Andrea Bezjak 1 1 Radiation Oncology, Princess Margaret Cancer Centre, Toronto, Canada. 2 Cancer Care Ontario, Ontario Health, Toronto, Canada. 3 Radiation Oncology, Cancer Centre of Southeastern Ontario, Kingston, Canada. 4 Radiation Oncology, The Ottawa Hospital, Ottawa, Canada Purpose/Objective: Thoracic reirradiation is a growing challenge faced by the MDT (1), with limited evidence to guide practice. This study aimed to characterise current practices in the technical aspects of thoracic reirradiation across Ontario and will inform consensus-based provincial guideline development. Material/Methods: In February 2025, a multidisciplinary working group was formed including physicians, radiation therapists and medical physicists, nominated for expertise in thoracic reirradiation from all 15 Ontario cancer centres. A 23-part survey was developed addressing institutional reirradiation policies, assessing the impact of previous radiotherapy, image registration, plan evaluation, quality assurance and workflow considerations. Distributed in May 2025, the survey was completed collaboratively by each centres’ MDT. Ontario, with 16 million residents, operates under a publicly funded universal healthcare system. Results: All centres (100%, 15/15 centres) responded. When image registration with the prior radiotherapy dataset
Purpose/Objective: Oligo-metastatic NSCLC represents an intermediate disease state where aggressive local treatments may yield improved outcomes. Consolidative radiotherapy to the primary lung lesion (CRT-L) has demonstrated some benefit, but the additional impact of incorporating ablative radiotherapy to all metastatic sites (CRT-LM) on overall survival, toxicity, and quality of life (QoL) remains inadequately defined. Material/Methods: In this randomized controlled study, 69 patients with histologically confirmed NSCLC with ≤ 3 metastatic sites and ECOG performance status ≤ 2, who responded to systemic therapy, were randomized to receive either CRT-L (n=31) or CRT-LM (n=38). Radiotherapy dosing and technique were according to institutional protocols. All patients underwent baseline and subsequent follow up with 18F-FDG WBPET-CT for disease evaluation. Toxicity was graded using CTCAE v5.0, and QoL was assessed using FACT-G and FACT-L. Kaplan-Meier survival analysis and log-rank testing were used to compare survival outcomes with additional subgroup analyses performed to explore potential prognostic factors. Results: CRT-LM arm showed a marked survival advantage with mean survival of 15 months versus 5 months. Median survival was not reached in the CRT-LM arm as over half of patients remained progression-free at last follow-up.Treatment was well tolerated with no grade ≥ 3 toxicities and preserved QOL.Subgroup analysis revealed distinct trends in outcomes based on mutation profile between the treatment arms.In the CRT-L group, patients with EGFR, ALK,ROS mutations had slightly better survival than mutation-negative.In the CRT-LM arm, patients with or without driver mutations (EGFR/ALK/ROS) achieved equally favorable survival outcomes with statistically no significant difference. This indicates that the benefit of consolidative ablative radiotherapy extends beyond molecular profiles, mitigating baseline prognostic differences.Overall, CRT-LM significantly improved survival ( χ² =32.25,p < 0.001) without added toxicity, establishing its role as an effective and safe consolidative strategy in oligometastatic NSCLC. Conclusion: Consolidative radiotherapy encompassing both the primary lung lesion and oligometastatic sites (CRT-LM) significantly enhances survival in oligometastatic NSCLC responding to systemic therapy, without increasing toxicity or compromising quality of life. The survival advantage of CRT-LM was consistent across clinical (Age,Gender,ECOG score,Smoking status) and molecular subgroups .These findings demonstrate CRT-LM as a safe, effective and practice-changing strategy that redefines the therapeutic landscape of oligometastatic NSCLC
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