Table 1.

Summary of antitumor effects of molecular hydrogen (H₂) in cellular models and animal models.

Experimental System	Cancer Types	Effects of Molecular Hydrogen (H2)	Ref. No.
Cultured cells	Human tongue cancer and Human fibrosarcoma	H2-rich electrolyzed water showed inhibitory effects on ROS production and cell proliferation.	[25]
	Human tongue cancer and Human fibrosarcoma	H2-dissolved water, in combination with platinum nano-colloid, showed enhanced suppression of ROS production and cell proliferation.	[26]
	Mouse Ehrlich’s ascites tumor	Nanobubble H2 water with platinum nano-colloid demonstrated inhibitory effects on the production of ROS and cell proliferation.	[27]
	Mouse Ehrlich’s ascites tumor	The combination of H2-dissolved water and platinum nano-colloid showed an inhibitory effect on cell proliferation, and the effect involved the transient generation of hydrogen peroxide.	[28]
	Human esophageal cancer	The combination of electrolytic H2 water and PVP-Pt colloid demonstrated enhanced inhibition of cell proliferation.	[29]
	Human cervical cancer, Human soft tissue tumor, etc.	Hydrogen radicals and H2 produced from Pd-Ni hydrogen storage alloys showed a killing effect on four types of tumor cells.	[30]
Experimental animals (Transplant models)	Mouse colon cancer	The combination of H2 water and 5-fluorouracil showed antitumor effects via activation of the apoptotic pathway.	[31]
	Human lung cancer	H2 gas showed antitumor effects through down-regulation of the expression of SMC3, a regulator of chromosome condensation.	[32]
	Mouse breast cancer and Human melanoma	The combination of palladium hydride and laser light irradiation was effective in suppressing tumor volume and tumor weight.	[33]
	Rat glioma and Human glioma	H2 gas inhibited the growth of glioblastoma through differentiation of glioma stem-like cells.	[34]
	Human endometrial cancer	H2-rich water showed antitumor effects by activating the ROS/NLRP3/caspase-1/GSDMD-mediated pyrotrophic pathway.	[35]
Experimental animals (Induced models)	UV-induced skin cancer	Hyperbaric treatment with H2 gas inhibited the growth and regression of skin cancer in mice induced by UV.	[8]
	Ionizing radiation-induced thymic lymphoma	H2-rich saline suppressed the development of thymic lymphoma in mice induced by ionizing radiation.	[36]
	High-fat diet-induced liver cancer	H2-rich water showed carcinogenic effects in an experimental system that progressed from NASH to fibrosis and liver cancer.	[37]
Angiogenesis	Co-culture experiment of 2 cell lines	Electrolyzed reduced H2 water inhibited lumen formation via suppression of VEGF expression in cultured cells.	[38]

H₂: molecular hydrogen; ROS: reactive oxygen species; PVP-Pt: platinum-poly(N-vinyl-pyrrolidone); NLRP3: nucleotide-binding and oligomerization domain-like receptor family pyrin domain containing 3; GSDMD: gasdermin D; UV: ultraviolet; NASH: nonalcoholic steatohepatitis; VEGF: vascular endothelial growth factor.