Antioxidant supplementation and cancer patients receiving curative-intent chemotherapy
Much of the advice in the lay press regarding the benefits of antioxidants for people undergoing cancer treatment does not qualify or differentiate between curative and palliative cancer treatment or the type of cancer treatment involved.
Curative treatment of most tumour types is based on the administration of multiple cycles of regularly scheduled chemotherapy. Chemotherapy dose intensity, a function of dose and frequency of administration, has been shown to correlate with outcome for some tumour types in prospective clinical studies.1 For this reason, granulocyte colony-stimulating factor support is standard treatment in most curative treatments of breast cancer as it enables dose intensity to be kept constant, which significantly improves disease-free and overall survival.2 Antioxidant supplements may compromise cancer patients’ chemotherapy dose, and therefore dose intensity, by protecting tumour cells from oxidative damage.3,4 The primary mechanism of action of many chemotherapy agents, such as the alkylating agents, anthracyclines, podophyllin derivatives, platinum compounds and camptothecins, is the generation of reactive oxygen species, which induces apoptosis in cancer cells. Antioxidant supplements may inhibit reactive oxygen species, thereby protecting cancer cells from death.