Early approaches aimed to promote antioxidant activity for anti-cancer effect targeted antioxidants and ROS-scavenging systems, such as superoxide dismutase (SOD), glutathione peroxidases, peroxidoxins, glutaredoxin, thioredoxin, catalase, and nuclear factor erythroid 2-related factor 2 (Nrf2). This evidence concerns the gene NFE2L2 and cancer.