“…Initially, the tumor microenvironment's weak acidity, hypoxia, and high glutathione levels affect radiotherapy's outcomes. 63 Secondly, although hypoxic cells release more ROS than normal cells, studies indicate that under hypoxic conditions, the antioxidant defense network in hypoxic cells is more actively engaged, quickly diminishing ROS damage to tumor cells. 64 Additionally, the hypoxic conditions within tumors can stimulate the expression of hypoxia-inducible factor HIF-1, which in turn promotes tumor cell proliferation and survival.…”