Undifferentiated sinonasal carcinoma may respond to single-fraction boron neutron capture therapy.

A large, rapidly progressing, unresectable undifferentiated sinonasal head and neck carcinoma regressed rapidly following single fraction boron neutron capture therapy (BNCT). The main toxicity consisted of mucositis lasting for a few days. The quality of life improved and was excellent until tumour recurrence 6 months after the date of BNCT.