Definitive Carbon-Ion Radiation Therapy for Locally Advanced Sinonasal Malignant Tumors: Subgroup Analysis of a Multicenter Study by the Japan Carbon-Ion Radiation Oncology Study Group (J-CROS)

Purpose: To evaluate the safety and efficacy of carbon-ion radiation therapy (C-ion RT) for locally advanced sinonasal malignant tumors in a multicenter retrospective study (J-CROS 1402 HN). Methods and Materials: Clinical data were collected for patients who had sinonasal malignant tumors of stage N0-1M0 and received C-ion RT at 4 institutions in Japan between November 2003 and December 2014. Of the 458 patients, 393 had naïve tumors and 65 had recurrent tumors. The tumors were located in the nasal cavity (n = 263), maxillary sinus (n = 109), ethmoid sinus (n = 71), and other locations (n = 15). The histologic types were mucosal melanoma (n = 221, 48%), adenoid cystic carcinoma (n = 122, 27%), squamous cell carcinoma (n = 31, 7%), olfactory neuroblastoma (n = 30, 7%), adenocarcinoma (n = 21, 5%), and other types (n = 33, 7%). Of the 458 patients, 300 (66%) had T4 tumors. All patients received definitive C-ion RT. Results: The median follow-up period was 25.2 months for all patients (range, 1.4-132.3 months). The 2-year overall survival and local control rates were 79.6% and 84.1%, respectively. As analyzed according to histology, the 2-year overall survival rate was 68.0% for mucosal melanoma, 96.8% for adenoid cystic carcinoma, 70.0% for squamous cell carcinoma, 96.7% for olfactory neuroblastoma, and 89.7% for adenocarcinoma. Regarding late toxicities, 17% of patients developed grade 3 and 4 toxicities, of which visual impairment was the most common. Conclusion: The results of our multicenter study have demonstrated that C-ion RT can provide excellent clinical outcomes with acceptable late toxicities in patients who have locally advanced sinonasal malignant tumors.