The relationship between posterior pharyngeal wall thickness and swallowing function after radiation therapy

Background: Dysphagia is a complication following radiation therapy (RT) for head and neck cancers (HNC). Radiologic findings of posterior pharyngeal wall thickening (PPWT) after RT has not been quantified and correlated to swallowing outcomes.Aims/objective: To evaluate PPWT and its impact on swallowing function following RT.Material and methods: Retrospective analysis of pre- and three-month post-RT PPWT, demographics, oncologic history, and swallowing parameters of patients undergoing RT for HNC. Multivariate analysis of variance was performed to evaluate the effect of PPWT on swallowing outcomes.Results: The mean age of the cohort (n = 207) was 61.8 (± 11.29) years. The mean PPWT increased by 0.28 (± 0.19) cm (p = .00) three-months after RT. A significant difference in PPWT score between tumor subsites, χ²(2) = 45.883, p = .00, with the highest mean rank score of 135.97 for nasopharynx and 103.46 for oropharynx. PPWT was significantly associated with increased pyriform sinus retention, higher Penetration-Aspiration Scale (PAS) scores and post-deglutitive aspiration (p < .05).Conclusions and significance: PPWT increase significantly after RT for HNC. Increased PPWT was associated with mean radiation dose to the nasopharynx and oropharynx and was an independent risk factor for increased pharyngeal residue, higher PAS scores, and timing of aspiration (p < .05).