Prospective observational study of patients treated with carbon-ion radiotherapy for non-squamous cell carcinoma of the head and neck in Gunma University

of the head and neck in 35 patients enrolled in a pective study at the Gunma University Heavy Ion Medical Center （from 2010 to 2014）. The median age of the patients was 59 years （range, 31-77 years）. The median follow-up time for all the patients was 65 months （range, 6.1-98.8 months）. Thirty-two and three patients received 64.0 Gy （relative biological effectiveness） and 57.6 Gy （relative biological effectiveness） in 16 fractions, respectively. The T-classification was 5/8/22 in T2/3/4, respectively, and the tumors were inoperable in 20 cases （57％）. The maxillary sinus and nasal cavity were the most common sites for tumors in 9 cases （26％）. Adenoid cystic carcinoma was dominant, with this carcinoma being found in 21 cases （60％）. The 5-year local control, progression-free survival, and overall survival rates were 74.5％, 53.2％, and 81.3％, respectively. Nine patients had local recurrence, and six patients died. Acute and late adverse events were evaluated according to the Common Terminology Criteria for Adverse Events, version 4.0. Over acute grade 3 radiation mucositis （8 cases） improved immediately with conservative therapy. Late grade 4 adverse events were observed; these were two cases of visual loss and one case of brain necrosis. There were no grade 5 adverse events. Carbon-ion radiotherapy achieved excellent local control and overall survival rates for non-squamous cell carcinoma.