Abstract / Summary
Purpose: Boron neutron capture therapy (BNCT) was approved in Japan in June 2020 as a curative option for unresectable, locally advanced, or recurrent head and neck cancers. Relevantly, its efficacy and safety in clinical practice should be regularly monitored, particularly regarding its optimal positioning. Therefore, to advance its clinical application, we assessed clinical data on BNCT for head and neck cancers. Methods: We retrospectively analyzed 285 patients who received initial BNCT between June 2020 and May 2024 with available ≥1 month follow-up data. The primary endpoint was local control (LC); secondary endpoints included progression-free survival (PFS), overall survival (OS), treatment response, and grade ≥ 3 adverse events. Results: The 2-year LC, PFS, and OS rates were 41.5%, 26.4%, and 59.2%, respectively. The complete response (CR), partial response (PR), and objective response (CR + PR) rates were 47.0%, 33.3%, and 80.4%, respectively. The cumulative incidence of grade ≥ 3 late adverse events was 14.0% at 2 years, with grade 5 adverse events occurring in 2.1% of patients. No significant differences were observed in LC or PFS among histological type subgroups; however, OS was significantly worse in patients with squamous cell carcinoma (SqCC) than in patients with non-SqCC. Regarding TNM stage at irradiation, radiation therapy at an early disease stage was significantly associated with improved LC. Conclusions: BNCT should be administered during the early disease stages when no other effective treatment options are available. Further studies should determine the factors contributing to treatment efficacy and safety, thereby optimizing multimodal treatment strategies involving BNCT.