S619
Clinical – Head & neck
ESTRO 2026
Digital Poster Highlight 3343 Outcomes of T1 Glottic Cancer Treated with Partial Laryngeal IMRT with Laryngeal Soft Tissue Matching Image Guidance Ranjan Subramani 1 , Alexander Rühle 1 , Jie Su 2 , Brian O'Sullivan 1 , John N Waldron 1 , Andrew Bayley 1 , Andrew McPartlin 1 , Scott V Bratman 1 , Andrew Hope 1 , Ali Hosni 1 , John Kim 1 , Nauman Malik 1 , John R de Almeida 3 , Christopher Yao 3 , Eric Monteiro 3 , Sharon Tzelnick 3 , Li Tong 1 , Wei Xu 2 , Shao Hui Huang 1 , Ezra Hahn 1 1 Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada. 2 Department of Biostatistics, Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada. 3 Department of Otolaryngology-Head & Neck Surgery, Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada Purpose/Objective: To report the outcomes of T1 glottic cancer patients treated with partial laryngeal IMRT using daily cone beam CT with laryngeal soft tissue matching for image-guidance (IG-IMRT), and to compare outcomes between moderately accelerated (ModAcc-RT) versus hypo-fractionated (Hypo-RT) radiotherapy regimens. Material/Methods: All patients with T1N0 glottic cancer treated with IG- IMRT from January 2008 to December 2021 were reviewed retrospectively from our prospective database. The gross tumor volume (GTV) was defined based on endoscopic findings and radiologic appearance, and expanded by 3-5 mm to generate a high-dose clinical target volume (CTV) and 10 mm for low-dose CTV, modified to follow routes of spread. Planning target volume (PTV) was generated with 5 mm circumferential and 10 mm cranio-caudal margin. RT regimens included ModAcc-RT (66-70 Gy in 33-35 fractions over 5.5-6.0 weeks, 2 Gy/fraction, 6 fractions/week, BID once per week) or Hypo-RT (51 Gy in 20 fractions/4 weeks, 2.55 Gy/fraction, 5 fractions/week; or 60 Gy in25 fractions/5 weeks, 2.4 Gy/fraction). The 51 Gy in 20 fractions regimen was typically reserved for lesions with minimal bulk. Outcome endpoints were local failure (LF), regional failure (RF), and distant metastasis (DM) estimated using the competing-risk method while disease-free survival (DFS) and overall survival (OS) were calculated using the Kaplan-Meier method. Results: A total of 299 patients were eligible: 196 (66%) with T1a and 103 (34%) with T1b disease. Seventy-four (25%) patients received ModAcc-RT, 221 (74%) Hypo- RT, and 4 (1%) Conventional-Fractionated-RT. Median follow-up was 5 years (IQR 3.6-6.1). A total of 15 LF (11 Hypo-RT vs 4 ModAcc-RT, p=0.874), 2 RF, and 2 DM were observed. All LFs were within the initial GTV. Five-
Conclusion Patients with pelvic SCC showed improved HRQoL after definitive RT, while patients with HNSCC did not. Patients with HPV negative HNSCC fared worse overall in HRQoL at 12 months than patients with HPV positive HNSCC irrespective of disease control. To our knowledge, these findings are not in line with previous reports and further research is needed to evaluate impact on HRQoL related to p16-status. References 1. Aaronson NK, Ahmedzai S, Bergman B et al. The European Organization for Research and Treatment of Cancer QLQ-C30: A Quality-of-Life Instrument for Use in International Clinical Trials in Oncology. JNCI J Natl Cancer Inst. 1993 Mar 3;85(5):365–76. 2. Bjordal K, Hammerlid E, Ahlner-Elmqvist M et al. Quality of Life in Head and Neck Cancer Patients: Validation of the European Organization for Research
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3. Osoba D, Rodrigues G, Myles J, Zee B, Pater J. Interpreting the significance of changes in health- related quality-of-life scores. J Clin Oncol Off J Am Soc Clin Oncol. 1998 Jan;16(1):139–44.
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