Interaction of High-Dose Antioxidant Vitamin Supplements in Cancer Treatment: A Dou-ble Sword?

High oxidative stress and increased reactive oxy-gen species (ROS) production accelerate tumor for-mation by triggering DNA damage, epigenetic chang-es, and genetic instability. The effects of antioxidant vitamins (A, C, and E) on cancer development and progression have long been investigated, with both protective and potentially risky results reported in the literature. Essentially, antioxidants reduce oxidative stress by neutralizing ROS, support immune function, and maintain cellular integrity. However, it is sug-gested that high-dose vitamin supplements, under certain conditions, can excessively suppress cellular oxidative balance, interfering with stress-response pathways in cancer cells and therefore leading to undesirable effects on treatment response, cell cycle, and apoptosis processes. For example, high-dose β-carotene use in vitamin A may increase the likelihood of lung cancer, particularly in high-risk individuals; vitamin C can exhibit both antioxidant and pro-oxidant effects depending on the dose and route of administration; Vitamin E is reported to have dual effects on tumor biology in addition to its anti-inflammatory properties. This review examines the mechanisms of vitamins A, C, and E on oxidative stress, inflammation, and cellular signaling pathways, evaluating their dual effects on cancer development and clinical processes, and summarizing key consid-erations for high-dose antioxidant use.