High oxygen levels can trigger apoptosis in cancer cells that overproduce oxygen free radicals.

“because they over produce oxygen free radicals in the context of high oxygen you can push the cells above their antioxidant potential and then trigger apoptosis so it's like a double-edge so it's a it's basically a u-shaped curve or inverted depending on how you want to think about it where exactly cancer cell is not only after by survivor it's optimized to thrive at a certain level of elevated reactive oxygen an elevated level but if you go too far it becomes counter”