A method for treating cancer, preventing cancer or delaying the progression of a cancer in an animal or human comprising the step of: administering to the animal or the human having a cancer a composition in an amount effective to treat cancer, prevent cancer or delay the progression of cancer in the animal or the human. The composition comprises a pharmaceutically acceptable excipient, and ascorbate which is joined to a carrier structure containing an anti-cancer active agent, said carrier structure being capable of releasing the anti-cancer agent in the presence of a reactive oxygen species.
