Efficacy and safety of boron neutron capture therapy for locally recurrent head and neck cancer.

[PURPOSE] Boron neutron capture therapy (BNCT) has emerged as a promising radiotherapy option for locally recurrent head and neck cancer (LRHNC). This study aims to evaluate the efficacy and safety of BNCT in patients with LRHNC and explore predictive factors for tumor control and overall survival.

[MATERIALS AND METHODS] A meta-analysis was conducted on the relevant studies up to April 2024 from PubMed, Embase, Cochrane, and Web of Science databases. The random-effects model was employed. The primary outcomes were the objective response rate (ORR), 2-year overall survival (2-year OS),and adverse events (AEs). Subgroup analysis was performed based on fraction design, the mean minimum dose (Dmin) of tumor, and histologic type.

[RESULTS] Seven studies involving a total of 361 patients were included. The ORR was 70 % (95 % CI: 65 %-75 %; P = 0.8187) and the 2-year OS rate was 45 % (95 % CI: 39 %-50 %; P < 0.0001). Subgroup analysis revealed that the ORR of multiple-fraction irradiation was essentially the same as single-fraction irradiation (76 % vs. 75 %), and a higher mean tumor Dmin correlated with significantly increased ORR and 2-year OS rates, with the remarkable effect at approximately 20 Gy (80 %vs. 54 %, 66 %vs.12 %). The ORR of patients with non-squamous cell carcinoma (NSCC) was higher than those with squamous cell carcinoma (SCC) (82 % vs. 72 %), while the 2-year OS rates were similar (50 % vs. 49 %). The most frequent acute AEs included hyperamylasemia (75 %, 95 % CI: 70 %-80 %), alopecia (61 %, 95 % CI: 55 %-67 %), and submandibular gland inflammation (61 %, 95 % CI: 49 %-72 %). The most common late AEs were alopecia (72 %, 95 % CI: 61 %-82 %), fatigue (35 %), and pain (27 %, 95 % CI: 12 %-46 %). The most frequent ≥ grade 3 acute AEs included hyperamylasemia (60 %, 95 % CI: 54 %-66 %), oral mucositis (11 %, 95 % CI: 7 %-14 %), and hemorrhage (11 %). The most frequent ≥grade 3 late AEs included cranial neuropathy (12 %), intracranial infection (8 %), and osteonecrosis of jaw (8%). The incidence of grade 3 and grade 4 acute AEs were 31.2 % and 5.7 %, respectively. There was only one case of grade 5 acute AE (0.4 %). Grade 3 and grade 4 late AEs were observed in 3.4 % and 0.4 % of patients, respectively. No grade 5 late AEs were reported. Severe AEs (SAEs) included carotid hemorrhage (4.8 %) and malnutrition (1.6 %).

[CONCLUSION] BNCT has shown favorable efficacy and safety in LRHNC. A high minimum tumor dose from BNCT correlated with a significantly increased response rate and survival. Further research is needed to support BNCT as a standard therapeutic option.