Abstract
BackgroundWe conducted a retrospective multicenter study to assess the clinical outcomes of carbon‐ion radiotherapy (CIRT) for head and neck malignancies (Japan Carbon‐Ion Radiation Oncology Study Group [J‐CROS] study: 1402 HN). We aimed to evaluate the safety and efficacy of CIRT in patients with external auditory canal (EAC) and middle ear (ME) carcinomas.MethodsThirty‐one patients treated with CIRT at four Japanese institutions were analyzed. Fourteen patients (45.2%) had squamous cell carcinomas, 13 (41.9%) had adenoid cystic carcinomas, and four (12.9%) had other types. Nineteen (61.3%), six (19.4%), three (9.7%), and three (9.7%) patients had T4, T3, T2, and T1 disease, respectively. All patients had N0M0 status. The median radiation dose was 64 Gy (relative biological effectiveness) in 16 fractions. The median gross tumor volume was 33.3 mL.ResultsThe median follow‐up period was 18.4 months (range, 5.1‐85.6). The 1‐ and 3‐year local control and overall survival rates were 75.0% and 55.0% and 79.3% and 58.7%, respectively. Regarding grade 3 or higher toxicities, three patients (9.7%) had grade 3 dermatitis, one (3.2%) had grade 3 mucositis, and two (6.5%) had grade 3 central nervous necrosis (ie, radiation‐induced brain necrosis). No grade 4 or worse reactions were observed.ConclusionCIRT was effective for EAC and ME carcinomas.
Highlights
Primary external auditory canal (EAC) and middle ear (ME) carcinomas are relatively rare diseases, with an incidence of one to six patients per 1 000 000 persons.[1,2] EAC and ME carcinomas are mainly treated with surgery
We evaluated the clinical outcomes of patients with EAC and ME carcinomas using data from Japan Carbon‐Ion Radiation Oncology Study Group (J‐CROS) 1402 HN
External auditory canal (EAC) and middle ear (ME) carcinomas are rare diseases and, to date, the use of carbon‐ion radiotherapy (CIRT) for EAC and ME carcinomas has only been evaluated in a single study, which was based on single‐institution data
Summary
Primary external auditory canal (EAC) and middle ear (ME) carcinomas are relatively rare diseases, with an incidence of one to six patients per 1 000 000 persons.[1,2] EAC and ME carcinomas are mainly treated with surgery. Further research is expected to focus on attempts to improve the survival of patients with locally advanced EAC and ME carcinomas. Several promising results of CIRT for head and neck cancers have been reported by a single institute.[6,7,8] The local control rate of EAC and ME carcinomas treated with CIRT was 54% after 3 years.[6]. J‐CROS 1402 HN was conducted as a retrospective survey of patients with a primary or recurrent head and neck malignancy who received CIRT in four institutions in Japan between November 2003 and December 2014. BED, biologically effective dose; fr, fractions; GTV, gross tumor volume; PS, performance status; RBE, relative biological effectiveness.
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