ESTRO 2025 - Abstract Book

S954

Clinical – Head & neck

ESTRO 2025

Purpose/Objective: Radiation-induced dysphagia in oral cavity cancers significantly impacts quality of life. While dysphagia’s link to doses received by swallowing organs like the pharyngeal constrictor muscles is well established, data on the base of tongue (BOT) are limited. The tongue base, essential for maintaining the bolus during swallowing is susceptible to radiation therapy (RT) damage, reducing tongue strength and coordination, causing dysphagia. This study analyzed the relation between BOT volumetric and dosimetric parameters and late dysphagia. Material/Methods: A retrospective single-center study was conducted on patients treated with IMRT between 2019 and 2023. All had oral cavity squamous cell carcinoma and underwent feeding tube (FT) placement before RT. The BOT was delineated, using deep learning-based automatic delineation and reviewed by a senior radiation oncologist. Late dysphagia was defined as FT dependency exceeding the 75th percentile (>442.5 days). BOT volume and dosimetric parameters (D0%-D10%-…-D100%) were tested as risk factors. Non-parametric tests were used, logistic regression, and ROC analysis to assess associations between BOT dose/volume and late dysphagia severity. Additionally, Kaplan-Meier analysis was performed to identify a threshold for BOT dose associated with late dysphagia risk. Results: Fifty-two patients (mean age 64 years, 25–86; 63% men) were included. 33% were cT3, 50% cT4; 75% underwent surgery; 73% received chemotherapy. The mean base BOT volume for the whole cohort was 18,2cm3 (range : 7,9 25,8). A significant difference was observed between the mean BOT volume of the low-risk group and the high-risk group for late dysphagia: 19,5cm3 (11-25,8) vs. 15,9cm3 (7,9-19,1) (p=0,02). Patients with a BOT volume < 19.12cm3 had a lower risk of late dysphagia (p=0,02). Univariate analyses showed no significant correlation between dosimetric parameters (D0–D100) and FT dependency. Nevertheless, the mean D50 for the whole cohort was 57,4 Gy (18,4-71,2) and there was a trend toward a difference between the mean D50 of the low-risk group and the high risk group for late dysphagia: 56,7 (18,4-71,2) vs. 59,5 (39,0-69,6). Patients with a D50 < 52.2 Gy had a lower risk of late dysphagia (p=0,96). Finally, a logistic regression model incorporating BOT volume and D50 demonstrated good performance in predicting late dysphagia, with an AUC of 0.74 (95% CI: 0.61–0.87). Conclusion: Patients with a low BOT volume had a higher risk of late dysphagia. For BOT volumes below 19.12 cm³, maintaining the D50 below 52.2 Gy may reduce the risk of dysphagia. References: Lazarus C, Logemann JA, Song CW, Rademaker AW, Kahrilas PJ. Effects of voluntary maneuvers on tongue base function for swallowing. Folia Phoniatr Logop. 2002;54 Jensen K, Lambertsen K, Grau C. Late swallowing dysfunction and dysphagia after radiotherapy for pharynx cancer: Frequency, intensity and correlation with dose and volume parameters. Radiother Oncol. oct 2007;85(1):74-82. Eisbruch A, Schwartz M, Rasch C, Vineberg K, Damen E, Van As CJ, et al. Dysphagia and aspiration after chemoradiotherapy for head-and-neck cancer: Which anatomic structures are affected and can they be spared by IMRT? Int J Radiat Oncol. déc 2004;60(5):1425-39 Keywords: Tongue base, Deglutiton disorder, radiotherapy