ESTRO 2025 - Abstract Book

S1030

Clinical – Head & neck

ESTRO 2025

Results: Total 30 patients were included in the study. Median age was 60.5 years (range: 37-84 years), 86.7% were male and 90% (n=27) were tobacco chewer/smoker with median 17.5 years of tobacco use. Total 2 (6.6%) patients were HPV positive and 2 were EBV positive (6.6%). Six patients (20%) had bilateral nodal disease at presentation, 73.3% had N3b node, 86.7% had multiple nodal level involvement with median nodal size of 5 cm (range 2-10 cm). Upront surgery was done in in 9 (30%) patients and 21 (70%) patients received chemoradiotherapy, of which 5 patients additionally received NACT. On response PET-CECT, of the 21 patients,14 (66.7%) had complete response, 3 (14.3%) had complete metabolic response with partial morphologic response, 2 had partial response, 1 had disease progression and 1 patient died of cardiac arrest before response assessment. At a median follow up is 31 months, 4 patients developed distant metastasis and 2 patients developed recurrent nodal failure on ipsilateral side. Only 1 patient developed a primary in vallecula after a median follow up of 25 months, within the irradiated mucosa.The 3 year overall survival is 74% and 3-year disease free survival is 74.1%. Acute grade-III dermatitis, mucositis and dysphagia was observed in 7.3%, 7.3% and 25.9% of the patients. Late toxicity data was available for 23 patients, none of the patients had late grade-III toxicity, 13.3% had grade-II skin fibrosis, 6.7% had grade-II xerostomia and 10% had late grade-II dysphagia. Total 9 patients developed hypothyroidism and 7 patients required thyroxin supplementation. Conclusion: There is low incidence of emergence of primary and acceptable toxicity following SMNI in HNCUP, may be considered as a middle ground between conservative and comprehensive irradiation. References: 1. Barker CA, Morris CG, Mendenhall WM (2005) Larynx-sparing radio therapy for squamous cell carcinoma from an unknown head and neck primary site. Am J Clin Oncol 28:445–448. 2. Lee NY, Riaz N, Lu JJ eds. Target Volume Delineation for Conformal and Intensity-Modulated Radiation Therapy . Cham: Springer International Publishing; 2015. 3. Maghami E, Ismaila N, Alvarez A, et al. Diagnosis and Management of Squamous Cell Carcinoma of Unknown Primary in the Head and Neck: ASCO Guideline. JCO . 2020;38:2570–2596. Keywords: Head & Neck, CUP, Selective Irradiation Digital Poster Bayesian analysis of dose to the medulla oblongata and dysphagia One-Year after head and neck radiotherapy Golnoosh Motamedi-Ghahfarokhi 1,2 , Gareth Price 1,2 , Isabella Fornacon-Wood 1,2 , Eliana M Vasquez Osorio 1,2 1 Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom. 2 Radiotherapy Related Research, Christie NHS foundation trust, Manchester, United Kingdom Purpose/Objective: Dysphagia is a common side effect of head and neck (HN) radiotherapy, reducing patients' quality of life [1]. Dose to the pharyngeal constrictor muscles (PCM) correlates with dysphagia [2]. Previous image-based data mining (IBDM) studies indicate an association between dose to the medulla oblongata (MO) and dysphagia one year post treatment [3]. This study aimed evaluates the predictive impact of mean dose to the MO and PCM on one-year dysphagia outcomes using Bayesian modelling. Material/Methods: Data from 104 oropharyngeal cancer patients treated with definitive (chemo) radiotherapy were analysed. Swallow function was assessed pre- and one year post-treatment using three dysphagia measures: MD Anderson Dysphagia 2482