Effects of antioxidants on cancer progression

Antioxidant supplements are widely marketed for their promised health benefits, including cancer prevention and therapy support. This belief stems from the idea that excessive levels of reactive oxygen species (ROS) cause oxidative damage to cellular macromolecules. However, the effects of antioxidants are highly context-dependent and influenced by the compound type, dosage, and cancer type. While antioxidants may slow tumor progression in specific cancers such as MYC-driven lymphoma, they can accelerate tumor growth, metastasis, and angiogenesis in other settings, including KRAS-driven lung cancer and BRAF-driven melanoma. Some antioxidants may also influence the immune system in ways that support cancer therapies, such as immune checkpoint blockade. Here, we review recent studies that highlight the complex roles of antioxidants in cancer progression and discuss their potential implications for clinical practice.