S790
Clinical - Lung
ESTRO 2026
Material/Methods: A retrospective cohort of patients with primary lung cancer who underwent curative or palliative thoracic radiotherapy between 2021 and 2024 was analyzed. Demographics, comorbidities, and oncologic treatments were evaluated and noted. SA and AV nodes were contoured according to Loap et al.’s A Radiotherapy Contouring Atlas for Cardiac Conduction Node Delineation. Mean heart, SA and AV node doses were extracted and converted to BED ₃ using the EQD ₂ model ( α / β = 3). Cardiac evaluation included baseline and post-treatment follow-up cardiology visits, with 12-lead ECGs. Associations between radiation dose and new-onset AF were analyzed using spline modeling to define cutoff values of mean heart, SA and AV node dose as continuous variables. Competing risk models of AF were assessed using Fine–Gray regression models. Results: A total of 84 patients (21 SCLC, 63 NSCLC) were included, mean age was 68.1±8.7 years and 83% were male. Additional characteristics of patients summarized in table 1a with a median follow-up of 18.1 26(3-35) months. The overall clinical AF incidence was 11%.( Figure 1) Univariable and multivariable Fine–Gray analyses identified higher SAN Dmax (sHR 1.03, p=0.040) and advanced age (sHR 1.09, p=0,001) as significant predictors of AF. Spline analysis determined cutoff values of 17.23 Gy for SA node Dmax and 14.47 Gy for AV node Dmax. Patients exceeding the SA node cutoff (>17.23 Gy) showed significantly higher AF incidence ( χ² =4.295, p=0.038).
Conclusion: In patients with advanced NSCLC with favorable response after first-line systemic therapy with ICIs, high-dose CTRT is associated with promising oncological outcomes and acceptable RP rate. The risk of acute RP seems higher in patients who received long-term ICI administration prior to CTRT. Keywords: Consolidative Thoracic RT, ICIs, Advanced NSCLC
Digital Poster Highlight 2491 Can Radiation Dose to the Sinoatrial and
Atrioventricular Nodes Predicts Atrial Fibrillation? Ilayda Yalman 1 , Hakan Yalman 2 , Halil Cumhur Yildirim 1 , Murat Cimci 2 , Deniz Kisinma Azaklioglu 1 , Kivanc Yalin 2 , Fazilet Oner Dincbas 1 1 Radiation Oncology, Istanbul University - Cerrahpasa,
Cerrahpasa Medical Faculty, Istanbul, Turkey. 2 Cardiology, Istanbul University - Cerrahpasa, Cerrahpasa Medical Faculty, Istanbul, Turkey
Purpose/Objective: Although radiation induced cardiac toxicity has been recognized for decades, the effects on cardiac substructures particularly the conduction system remain poorly defined. This study aimed to evaluate the impact of radiation dose to the sinoatrial (SA) and atrioventricular (AV) nodes on the new onset of clinical atrial fibrillation (AF) and to identify other factors influencing AF risk in patients receiving thoracic radiotherapy.
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