Pilot Feasibility and Safety Study of Hydrogen Gas Inhalation in Locally Advanced Head and Neck Cancer Patients

Purpose: Hydrogen (H2) gas inhalation might alleviate acute radiotherapy toxicities by scavenging free radicals produced by ionizing radiation and anti-inflammatory properties. This study aimed to investigate the feasibility and safety of H2 gas inhalation during concurrent chemoradiotherapy (CCRT) in patients with locally advanced head and neck cancer (LAHNC). Patients and Methods: We designed a pilot prospective study combining CCRT with aerosol inhalation of H2 gas. Each patient was scheduled to receive daily intensity-modulated radiotherapy (IMRT) in 33 fractions on a weekday and six cycles of weekly chemotherapy. All patients inhaled H2 gas through a cannula or mask 1 hour per day, 1-2 hours before IMRT. The primary endpoint was the feasibility of H2 inhalation. Eighty percent of the patients who completed at least 20 applications of H2 gas inhalation were considered feasible. The secondary endpoints were safety profiles during H2 gas inhalation (vital signs and symptoms related to H2 gas inhalation) and acute toxicities during CCRT. Results: We enrolled 10 patients with LAHNC between July 2023 and December 2023. All patients received 33 fractions of H2 gas inhalation on the same day as the IMRT. Vital signs during and at the end of H2 gas inhalation were stable in all patients. None of the 10 patients had hypertension or hypotension during any of the 33 inhalations. No adverse events related to H2 gas inhalation, such as cough, nasal bleeding, dizziness, headache, nausea, or vomiting, were reported. Grade 3 leukopenia was found in two patients (20%) during the 5th week of CCRT. Grade 2 radiation dermatitis and pharyngitis were found in three patients (30%). Conclusion: H2 gas inhalation combined with CCRT is feasible and safe for patients with LAHNC.