Social media users are sharing claims that rubbing hydrogen peroxide onto the skin can treat cancer and that oxygen can kill cancer cells. “Neither hydrogen peroxide nor oxygen has undergone the rigorous scrutiny and testing needed to prove that these therapies can treat cancer or kill cancer cells,” Tyler Johnson, a clinical assistant professor of oncology at Stanford Medicine, said via email. While application of hydrogen peroxide can reach the bloodstream, he explained, it will not reach to a tumor far enough to have any helpful effect – in fact, "large amounts of ingested hydrogen peroxide are known to be toxic and cause internal burns." “The most highly touted ‘hyperoxygenating’ agents are hydrogen peroxide, germanium sesquioxide, and ozone,” the review explains. There is no evidence that rubbing hydrogen peroxide on the skin, consuming it, or using other unproven methods to increase oxygen in the body will have an effect on cancer cells.

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