Commentary: Antioxidants for cancer: New tricks for an old dog?

Traditionally, the main focus of the importance of reactive oxygen species (ROS) in oncology is that these species induce DNA damage, leading to a predisposition to cancer. However, it has recently been shown that ROS may have an alternative activity, by modulating tumor cell signaling. Moreover, tumor cell signaling mediated by ROS is readily reversible upon treatment with antioxidants. This emerging evidence on the molecular effects of antioxidants on tumor cells, along with the evidence that the route of administration of antioxidants in earlier clinical trials for cancer could not achieve pharmacologically effective levels, suggests that antioxidants may serve as bona fide signal transduction modifiers for cancer. A re-examination of the current evidence and further study is clearly warranted.