Preliminary study of intensity-modulated carbon ion reirradiation for locoregionally recurrent nasopharyngeal carcinoma after definitive IMRT——Clinical experience from Shanghai Proton Heavy Ion Hospital

Abstract

Objective To evaluate the short-term efficacy and toxicities of intensity-modulated carbon ion radiotherapy (IMCT) for patients with locoregionally recurrent nasopharyngeal carcinoma after intensity-modulated radiotherapy (IMRT). Methods A total of 112 patients with locoregionally recurrent nasopharyngeal carcinoma undergoing salvaging IMCT between May 2015 and February 2018were enrolled in the study. All patients previously received one course of definitive X-ray IMRT. Among them, 10 patients (9%) were diagnosed with stage Ⅰ, 26 patients (23%) with stage Ⅱ, 41 patients (37%) with stage Ⅲ and 35 patients (31%) with stage Ⅳnasopharyngeal carcinoma, respectively. The median age of the cohort was 48 years (range, 17-70 years) old. The median dose to the gross tumor volume (GTV) was 60 GyE (range, 50-69 GyE). Results With a median follow-up time of 20 months (range, 5-45 months), 20 patients died and 42 patients developed local recurrence. The 2-year overall survival (OS) and local progression-free survival (LPFS) rates were 85% and 52%. Both univariate and multivariate analyses demonstrated that stage Ⅳ disease was associated with significantly worse OS. No predictors were found for LPFS. No acute toxicity of grade 3 or higher was observed during reirradiation. Severe (grade 3 or above) late toxicities included xerostomia (n=1), hearing impairment (n=2), temporal lobe injury (n=1) and mucosal necrosis (n=19). Conclusions IMCT is an efficacious and safe treatment for patients with locoregionally recurrent nasopharyngeal carcinoma with acceptable toxicity profile. Long-term follow-up is necessary to further evaluate the long-term efficacy and late toxicities. Key words: Nasopharyngeal neoplasm/intensity-modulated carbon ion radiotherapy; Second-course radiotherapy; Treatment outcome