ESTRO 2025 - Abstract Book

S1387

Clinical - Lung

ESTRO 2025

Results: 5/10 patients have been recruited from June-November 2024. Median age was 78 (Range 74-84) and 3/5 (60%) were female. Eastern Cooperative Oncology Group Performance Status (ECOG PS) was 1 for three patients and 2 for two patients. The technical feasibility 8-hour target has been achieved for all patients. Participant overall satisfaction was ranked as very high for all patients. Conclusion: Early indications suggest people with ELC can safely have CT simulation, planning and SFSABR treatment within a single working day. This may be a particularly attractive option for those living in remote areas or when multiple hospital visits are a barrier to accessing curative treatment.

Keywords: SABR, Single-Fraction, Early NSCLC

References: 1. Ball D, et al. Lancet 2019. DOI: 10.1016/S1470-2045(18)30896-9

2. Videtic et al. Int J Radiat Oncol Biol Phys 2015. DOI: 10.1016/j.ijrobp.2015.07.2260 3. Singh et al. Int J Radiat Oncol Biol Phys 2019. DOI: 10.1016/j.ijrobp.2019.08.019 4. Siva et al. JAMA Oncol 2021. DOI: 10.1001/jamaoncol.2021.2939

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Proffered Paper Consolidation ICI alters cardiac subregion radiosensitivity in lung cancer patients treated with chemo radiotherapy Yejin Kim 1 , Gowoon Yang 2,3 , Jaewon Oh 4 , Seo-Yeon Gwak 4 , Kyunghwan Kim 2 , Joongyo Lee 2 , Jin Sung Kim 2 , Chang Geol Lee 2 , Jae Ho Cho 2 , Bonnie Ky 5 , Hong In Yoon 2 , Clemens Grassberger 1 1 Radiation Oncology, University of Washington, Seattle, USA. 2 Radiation Oncology, Yonsei University College of Medicine, Seoul, Korea, Republic of. 3 Radiation Oncology, Cha University School of Medicine, Ilsan, Korea, Republic of. 4 Cardiology Division, Yonsei University College of Medicine, Seoul, Korea, Republic of. 5 Cardio-Oncology, University of Pennsylvania, Philadelphia, USA Purpose/Objective: Chemoradiotherapy (CRT) is the main treatment for locally advanced non-small cell lung cancer (NSCLC) 1 . Recently, the addition of immune checkpoint inhibitors (ICIs) as consolidation therapy after CRT has emerged as a new standard of care, markedly improving survival rates 2,3 . While cardiac toxicity of CRT has been widely investigated over decades, the cardiotoxicity of CRT combined with ICI remains underexplored. This study assesses if ICI exposure alters the critical cardiac subregion linked to radiation-induced heart disease (RIHD) following CRT. Material/Methods: We conducted a retrospective analysis of 321 NSCLC patients treated with definitive CRT from August 2008 to December 2019, including 67 who received consolidation ICI. Cardiac contours include the entire heart, left/right atriums, left/right ventricles, major coronary arteries, and conduction nodes. The primary endpoint was RIHD, defined as a major adverse cardiac event and atrial fibrillation. We used Fine-Gray models to investigate associations between RIHD and mean doses to cardiac subregions while accounting for the competing risk of non RIHD related death. Additionally, we used voxel-based analysis (VBA) to investigate the correlation between three dimensional cardiac dose distributions and 1-year survival 4 . Results: The 2-year cumulative incidence of RIHD was 18.4%, with no significant difference between CRT and CRT+ICI groups (18.1% vs. 13.2%, p=0.43). Doses to cardiac subregions were similar between the groups. In the CRT group,