Table 1.

Metal oxide NPs with anticancer activity by direct action on tumor cells in different in vivo models.

Metal Oxide NPs	In Vivo Model	NP Size	Authors	Reference
Cerium oxide	Orthotopic injection of pancreatic cancer cells in athymic nude mice	5–8 nm	Wason et al., 2013	[26]
Cerium oxide	Xenografted mice injected with melanoma cells	3–5 nm	Ailili et al., 2013	[35]
Titanium dioxide	Human oral squamous cell carcinoma tumor in mice	50 nm	Lucky et al., 2015	[25]
Copper oxide	Subcutaneous melanoma in mice	40–110 nm	Wang et al., 2013	[54]