Exploring the Interplay Between Radiotherapy Dose and Physiological Changes in the Swallowing Mechanism in Patients Undergoing (Chemo)radiotherapy for Oropharynx Cancer.

This study explored associative relationships between radiotherapy dose volumes delivered to the dysphagia aspiration risk structures (DARS) and swallowing physiological disturbance at 3 months post treatment in a homogenous cohort of patients who received (chemo)radiotherapy ((C)RT) for oropharyngeal head and neck cancer (HNC). Participants(n = 53) were a subgroup of patients previously recruited as part of a prospective randomised trial, and had undergone physiological swallowing assessment using videofluroscopic swallowing study (VFSS) at 3 months post (C)RT. The extended oral cavity (EOC), supraglottic larynx (SGL), glottic larynx (GL), cricopharyngeal inlet (CI), and pharyngeal constrictor muscles (PCM) were contoured as per international consensus guidelines and dose volume histograms (DVHs) were generated for each structure. Each DVH was analysed to reveal mean, maximum and partial radiotherapy doses of V40, V50 and V60 for each structure. Physiological swallowing function on VFSS was rated using the Modified Barium Swallow Impairment Profile (MBSImP). A binary logistic regression model was used to establish associative relationships between radiotherapy dose to the DARS and physiological changes within the swallowing mechanism. Structures that received the largest volumes of radiotherapy dose were the PCM and SGL. Significant relationships were found between the proportion of the EOC, SGL, GL and PCMs that received radiotherapy doses > 40 Gy, > 50 Gy and > 60 Gy and the likelihood of a moderate-severe physiological swallowing impairment (on the MBSImP). Whilst the current study was exploratory in nature, these preliminary findings provide novel evidence to suggest structure-specific associative relationships between radiotherapy dose and impacts to corresponding swallow physiology in patients with oropharyngeal HNC.