Radiation-induced late dysphagia after intensity-modulated radiotherapy in nasopharyngeal carcinoma patients: a dose-volume effect analysis

Li Jiang,Tong Wu,Yong Zhang,Chenhui Huang,Xiaobi Tang,Yiru Wang,Rensheng Wang,Yixiu Gan

doi:10.1038/s41598-018-34803-y

Abstract

Dysphagia is a side effect of nasopharyngeal carcinoma chemo-radiotherapy (CRT) which greatly influences the quality of life of the patients. We analyzed late dysphagia in 134 patients with nasopharyngeal cancer undergoing radical radiotherapy (RT), and correlated these findings with dose–volume histogram (DVH) parameters of the swallowing organs at risk (SWOARs). DVH parameters of SWOARs were correlated with late dysphagia, and with RTOG/EORTC scale score and the M. D. Anderson dysphagia inventory (MDADI) score. The mean dose (Dmean) to the superior and inferior constrictor muscles (SCM and ICM) and age were associated with grade 2 late dysphagia. Receiver operating characteristic (ROC) curves showed that the threshold values for grade 2 late dysphagia were: Dmean to SCM ≥ 67 Gy, partial volume receiving specified dose of 60 Gy (V60) of SCM ≥ 95%, Dmean to ICM ≥ 47 Gy, and V50 of ICM ≥ 23%. The areas under the ROC curve were 0.681 (p = 0.02), 0.677 (p = 0.002), 0.71 (p < 0.001) and 0.726 (p < 0.001) respectively. Our study demonstrates a significant relationship between late dysphagia and the radiation doses delivered to the SCM and ICM. Our findings suggest that physicians should be cautious in reducing the RT dose to SWOARs in order to avoid severe dysphagia. Further prospective trials are necessary to recommend this as part of routine clinical practice.

Highlights

Nasopharyngeal carcinoma (NPC) is a common malignancy in Southern China, especially in Guangdong and Guangxi provinces[1,2]
The newly diagnosed NPC patients who suffered from dysphagia before treatment were still excluded so as to ensure that the observed dysphagia was only induced by radiation-related swallowing organs at risk (SWOARs) dysfunction but not by lower cranial neuropathy
We divided the patients into Group 1 and Group 2 based on the severity scores of dysphagia, and found that age and gender were related to the grade level of late dysphagia in the univariate analysis (p < 0.05)

Summary

Introduction

Nasopharyngeal carcinoma (NPC) is a common malignancy in Southern China, especially in Guangdong and Guangxi provinces[1,2]. Late dysphagia has emerged as a common side effect of NPC radiotherapy[4,5]. Late dysphagia is associated with swallowing-related structures, tumor, and treatment[6,7]. The IMRT dose tolerances of the swallowing-related structures are poorly characterized. It is necessary to further study the radio-tolerance of SWOARs in NPC patients receiving IMRT. We retrospectively reviewed the clinical and dosimetric data of a cohort of NPC patients who developed late dysphagia after IMRT, and performed dose-volume outcome analysis to determine the effect of different doses on swallowing-related structures. Dose–volume parameters and the observed incidence of late dysphagia in these patients. After a re-contouring of the SWOARs according to recently published guidelines, we determined the dose tolerated by the SWOARs that achieved the highest uncomplicated tumor control

Methods

Results

Discussion

Conclusion