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.