Table 2.

Main mechanism of gastric cancer induced by each kind of heavy metal.

Heavy metals	Main mechanism	Reference
Cd	(1) Disrupt the stomach mucosal barrier	[19–21, 23, 24, 26–30]
	(2) DNA damage via ROS
	(3) Ineffective DNA repair
	(4) Alter catalase activity
	(5) Accelerate cancer development
As	(1) Cell damage	[23, 24, 30–33]
	(2) Inhibit DNA repair
	(3) Epigenome
	(4) Enhanced cancer development by inducing overexpressing of miRNAs
Hg	(1) DNA damage	[24, 28, 34–36]
	(2) Chromosomal aberration
	(3) Induce immune dysfunction
Pb	(1) DNA damage via ROS	[22–24, 28, 30, 37–39]
	(2) Ineffective DNA repair and inhibiting DNA repair with UItraviolet rays
	(3) Promote tumorigenesis via Il-8
	(4) Change catalase activity
	(5) Enhanced cancer development by inducing overexpressing of miRNAs
Cr	(1) DNA lesion	[23, 24, 32, 33, 40–42]
	(2) Gene abnormalities
	(3) Promote cancer cell migration and invasion