Comparison of otologic complications between intensity-modulated and two-dimensional radiotherapies in nasopharyngeal carcinoma patients

Abstract

Objective: To investigate the otologic complications in patients with nasopharyngeal carcinoma (NPC) who were treated by intensity-modulated radiotherapy (IMRT) and compared with those who were treated by two-dimensional radiotherapy (2DRT).

Study design: A historical cohort study was performed comprising NPC patients who underwent IMRT or 2DRT at Chung Shan Medical University Hospital.

Setting: Chung Shan Medical University Hospital.

Subjects and methods: Twenty-six NPC patients treated by IMRT (group A) and 18 NPC patients treated by 2DRT (group B) were enrolled. All patients underwent otoscopy, audiometry, and a vestibular-evoked myogenic potential (VEMP) test at a mean interval of three years after irradiation.

Results: Although groups A and B did not significantly differ in the occurrence rate of otitis media with effusion (OME), group B had a significantly greater occurrence rate of chronic otitis media than group A (P < 0.05, χ(2) test). The incidences of high-frequency sensorineural hearing loss were 46 percent in group A and 67 percent in group B, with no significant difference between the two. In terms of VEMPs, group A had a significantly lower abnormal rate (31%) than group B (61%; P < 0.05, χ(2) test). In addition, a significant relationship existed between T stages and OME in NPC patients treated by IMRT (P < 0.01, Fisher-Freeman-Halton test) but not by 2DRT.

Conclusion: The incidence of chronic otitis media and abnormal VEMPs in NPC patients treated by IMRT were significantly lower when compared with those treated by 2DRT, demonstrating the superiority of IMRT in decreasing unwanted otologic complications. However, occurrence of OME, which was related with advanced T stage, cannot be reduced by IMRT.