S844
Clinical - Lung
ESTRO 2026
visualized the unadjusted association between DTI duration and OS. Multivariable Cox proportional hazards models evaluated the association between DTI duration and OS and cancer-specific survival (CSS) adjusting for patient (e.g., age, comorbidities), disease (e.g., anatomic location, tumour size) and system (e.g., rurality, treatment era) factors. Restricted cubic spline analyses assessed linearity of the exposure in the Cox models. We conducted four sensitivity analyses in the OS analysis: included patients with squamous cell carcinoma, censored follow-up on January 1, 2020, excluded patients with previous cancer diagnosis, included patients with thoracic surgery consultation within DTI duration. Results: Results: The cohort included 532 patients. The median DTI duration was 61 (interquartile range: 46–79) days. The Kaplan Meier method indicated a trend of longer DTI durations being associated with worse OS. No evidence of a more complex non-linear relationship between DTI duration and OS, nor CSS, was identified. The adjusted Cox models indicated every 1-week (aHR=1.04 (95% CI=1.01–1.08)), and 4-week (aHR=1.19 (95% CI=1.03–1.38)) increase in DTI duration was associated with worse OS. These findings remained consistent in sensitivity analyses. Moreover, every 1- week (aHR=1.05 (95% CI=1.01–1.10)), and 4-week (aHR=1.22 (95% CI=1.03–1.45)) increase in DTI duration was associated with worse CSS. Conclusion: Conclusion: The DTI duration should be as short as reasonably achievable in patients with stage I non- adenocarcinoma NSCLC treated with SBRT to optimize outcomes. References: 1 Jalink M, King WD, Anderson BO, et al. Recommendations for studying the association of the cancer diagnosis to treatment interval with overall survival: a modified Delphi process. Br J Cancer. Published online September 5, 2025. doi:10.1038/s41416-025-03158-3. Keywords: lung cancer, treatment delay, overall survival Impact of breathing motion on a novel artificial intelligence model used to screen treatment planning imaging for interstitial lung disease (ILD) Andrew J Hope 1,2 , Simon R van Kranen 3 , Chris McIntosh 2,4 , Sonja Kandel 5 , Tony Tadic 2 , Tirth Patel 2 , Jan Jakob Sonke 3 1 Radiation Oncology, University of Toronto, Toronto, Canada. 2 Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Canada. 3 Radiation Oncology, The Digital Poster 4493
(2018). Impact of Interstitial Lung Disease Classification on the Development of Acute Exacerbation of Interstitial Lung Disease and Prognosis in Patients with Stage III Non-Small-Cell Lung Cancer and Interstitial Lung Disease Treated With Chemoradiotherapy. Journal of Cancer, 9(11), 2054- 2060. https://doi.org/10.7150/jca.24936. Keywords: interstitial lung disease, lung cancer, toxicity Digital Poster Highlight 4492 Time to treatment with stereotactic body radiation therapy and overall survival for non- small cell lung cancer Cassidy Laub 1,2 , Paul Nguyen 3 , Matthew Jalink 2,4 , Timothy Owen 5 , Martin Korzeniowski 5 , Allison Ashworth 2,5 , Catherine L. Goldie 6,7 , Timothy P. Hanna 2,5 1 Department of Medicine, Queen's University, Kingston, Canada. 2 Division of Cancer Care and Epidemiology, Queen's University, Kingston, Canada. 3 ICES Queen’s, Queen's University, Kingston, Canada. 4 Department of Public Health Sciences, Queen's University, Kingston, Canada. 5 Department of Oncology, Queen's University, Kingston, Canada. 6 Queen’s Collaboration for Health Care Quality, A JBI Centre of Excellence, Kingston, Canada. 7 School of Nursing, Queen's University, Kingston, Canada Purpose/Objective: Background: Understanding how the diagnosis to treatment initiation (DTI) duration affects overall survival (OS) is relevant for improving patient outcomes and informing health policy. However, there is no evidence investigating this relationship in stage I non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiation therapy (SBRT). Our objective was to investigate the association between DTI duration and OS for stage I non-adenocarcinoma NSCLC patients treated with SBRT in Ontario, Canada. Material/Methods:
Methods: We conducted a population-based retrospective cohort study with linked health
administrative data from Ontario, Canada’s single payer universal health system. This study represents the first application of newly published international consensus-based recommendations for investigating the association between DTI duration and OS.1 The cohort included Ontario patients diagnosed with stage I NSCLC between January 1, 2010, and June 30, 2019, treated with SBRT. Adenocarcinomas were excluded due to histological heterogeneity not controllable within the available data. A landmark analysis using an a priori landmark time of 5 months from diagnosis addressed concerns of immortal time bias and the wait time paradox. The Kaplan Meier method
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