Dose-volume relationship for laryngeal substructures and aspiration in patients with locally advanced head-and-neck cancer

Literature has shown a significant relationship between radiation dose to the larynx and swallowing disorders. We prospectively studied the dose-volume relationship for larynx substructures and aspiration. Forty nine patients with stage III/IV head-and-neck (H&N) squamous cell carcinoma were prospectively enrolled in this IRB-approved, federally funded study. All patients received IMRT-based chemoradiation therapy (CRT) and were scheduled for videofluorography (VFG) prior to CRT and at 3, 6, 9, 12, and 24 months post-CRT. Twelve laryngeal substructures were contoured in each patient: thyroid cartilage, cricoid cartilage, total epiglottis, suprahyoid epiglottis, infrahyoid epiglottis, total larynx, supraglottic larynx, subglottic larynx, glottic larynx, arytenoids, aryepiglottic (AE) folds, and glossoepiglottic fold. After exclusions, 29 patients were included in the final analysis. Incidence of aspiration at 1 year following CRT was correlated with dose-volume data to laryngeal substructures using logistic regression. The median age was 54 years with 79% being non-smokers. Tumor sites included oropharynx (22), unknown primary (6), and hypopharynx (1). One year following CRT, 10/29 (34%) showed aspiration on VFG. Dose to the AE folds showed the highest correlation with aspiration at 12 months and was significant on multivariate analysis (p = 0.025). A mean dose cutpoint of 6500 cGy or higher to the AE folds was associated with an increased risk of aspiration at 1 year [positive likelihood ratio (+LR) 2.81, positive predictive value (PPV) 60%, negative predictive value (NPV) 92.9%, relative risk (RR) 8.4]. In this analysis, mean dose to the AE folds was associated with an increased risk of aspiration at 1 year. However, these are hypothesis-generating data that require further research and validation in a larger patient subset.