Definitive carbon-ion radiotherapy for locally advanced parotid gland carcinomas

BACKGROUND: The purpose of this study was to present our evaluation of the safety and efficacy of carbon-ion radiotherapy (C-ion RT) for locally advanced parotid gland carcinomas. METHODS: Clinicopathological features and outcomes were evaluated in 46 patients receiving C-ion RT for parotid gland carcinomas. RESULTS: Sixteen patients had adenoid cystic carcinoma; 8 had adenocarcinoma, 8 had mucoepidermoid carcinoma, and 14 had other carcinomas. T2, T3, T4a, and T4b diseases were diagnosed in 3, 18, 8, and 17 patients, respectively. C-ion RT was provided to 25 patients as the primary treatment, to 20 patients for local recurrences after surgery, and to 1 patient for residual tumor after surgery. During follow-up (median duration, 62 months), 5-year local control and overall survival (OS) rates were 74.5% and 70.1%, respectively. Of the 30 patients without facial nerve palsy before C-ion RT, 25 showed no radiation-induced facial nerve palsy. CONCLUSION: C-ion RT is effective and has acceptable toxicity levels for locally advanced parotid gland carcinomas.