Dysphagiaafter Definitive Intensity-modulated Radiation Treatment For Nasopharyngeal Cacinma

Purpose:To evaluate late dysphagia after intensity modulated radiaton therapy（IMRT）for nasopharyngeal cacinoma（NPC）,and to examine its correlation with dose-volume histograms（DVHs）of the pharyngeal constrictor muscles.Methods:A total of 134 patients with NPC undergoing primary IMRT were enrolled.Swallowing was evaluated by RTOG/EORTC scale and the M.D.Anderson dysphagia inventory（MDADI）.Clinical and dosimetric parameters were correlated with late dysphagia.Results: With a median follow-up of 34 months（range 25-44months）,71patients（53.0%）were reported late dysphagia.Mean dose to the whole pharyngeal constrictor muscle（PCM）and its components（the superior,middle and inferior constrictor muscle,SCM,MCM,ICM）,SCMv60,MCMv50,MCMv60,ICMv50,the age and the sex were associated to late dysphagia at univariate analysis.The age（OR 1.050,P=0.031）、 Mean dose to the SCM（OR1.170,P=0.027）and ICM（OR 1.251,P=0.004）was the only statistically significant predictor of late dysphagia at the multivariable analysis.PCMmean> 60Gy、SCMmean>67Gy and V60>95%、ICMmean>47Gy and V₅₀>23% was the threshold value of predicting grade 2 late dysphagia.Conclusion: Radiation-induced late dysphagia after IMRT for NPC patients was common.The late dysphagia correlates to the irradiated volume and dose to whole pharyngeal constrictor muscles,SCM,and MCM.This finding suggests a potential advantage in reducing the RT dose swallowing structures to avoid severe dysphagia.However,further prospective trials are needed.