Dose-Volume Relationship For Laryngeal Substructures And Aspiration In Patients With Head And Neck Cancers

Published literature has shown a significant relationship between radiation dose to the larynx and aspiration. It is unclear which laryngeal substructures, when irradiated, are most associated with swallowing disorders. We aim to prospectively study the dose-volume relationship for larynx substructures and aspiration. Forty-nine patients with stage III/IV local-regional advanced head-and-neck squamous cell cancer were prospectively enrolled in this IRB-approved, federally funded study. All patients received IMRT based radiation + chemotherapy (CRT) and were scheduled for videofluorography (VFG) prior to CRT and 3, 6, 9, 12 and 24 months post CRT. The following substructures of larynx were contoured in each patient: thyroid cartilage, cricoid cartilage, arytenoids, suprahyoid epiglottis, infrahyoid epiglottis, total epiglottis, aryepiglottic folds, supraglottic larynx, glottic larynx, subglottic larynx and total larynx. Of these 49 patients, 30 were included for this analysis. Nineteen patients were excluded due to either prevalent aspiration at baseline, or because they did not come to have their 12 month evaluation. The incidence of aspiration 1 year following CRT was correlated with dose-volume data to laryngeal substructures. Doses were compared between those with and without aspiration at 12 months using the Wilcoxon rank sum test. Data are reported as mean (standard deviation). There were few data points at 24 months. For the 30 included patients, the median age for the group was 50 years, 23 males, 7 females, 63% were smokers and 93% had stage IV disease. None of the 30 patients aspirated prior to CRT. One year following CRT, 10/30 (33%) showed aspiration on VFG. The following dose-volume associations were observed. Aryepiglottic Folds: The mean dose was significantly higher in patients who aspirated than in non-aspirating patients (6600 cGy (521) vs 5830 cGy (1024), P = 0.048), V50, V60, D20 and D1.5cc also were significantly associated with aspiration (P < .05). Suprahyoid Epiglottis and Total Epiglottis: Mean dose and D1.5cc were significantly associated with aspiration (mean 7280 cGy (442) in aspirators, 6755 cGy (661) in non-aspirators, P = 0.048). Cricoid Cartilage: V40 was significantly associated with aspiration (P < .05). Entire Larynx: The mean dose was higher in aspirators, 7090 cGy (572) compared with non-aspirators, 6290 cGy (943), P = 0.059. V40, V60, D15 and D20were significantly associated with aspiration. These are hypothesis-generating data that require further research and validation in a larger number of patients to assess the importance of laryngeal substructures in aspiration so IMRT can be used to reduce radiation doses to the selected OAR within the larynx.