Table 1.

Keyword Applied during the Identification Phase

Database	Search String
Cochrane	(“molecular hydrogen” OR “hydrogen therapy” OR “hydrogen treatment” OR “hydrogen gas” OR “hydrogen water” OR “hydrogen inhalation” OR “hydrogen-rich”) AND (“cancer” OR “carcinoma” OR “tumor” OR “tumour”)
PubMed	(“molecular hydrogen” OR “hydrogen therap*” OR “hydrogen treatment” OR “hydrogen gas” OR “hydrogen water” OR “hydrogen inhalation” OR “hydrogen-rich”) AND (“cancer” OR “carcinoma” OR “tumor” OR “tumour”)
Google Scholar	(“molecular hydrogen” OR “hydrogen therapy” OR “hydrogen therapeutic” OR “hydrogen treatment” OR “hydrogen gas” OR “hydrogen water” OR “hydrogen inhalation” OR “hydrogen-rich”) AND (“cancer” OR “carcinoma” OR “tumor” OR “tumour”)