High rate of metabolic activities in cancer cells increases ROS levels and the activation of ROS-sensitive oncogenic pathways through the activation of transcription factors, such as nuclear factor-κB (NF-κB), activator protein-1 (AP-1), hypoxia-inducible factor-1α (HIF-1α) and signal transducer and activator of transcription 3 (STAT3) [11–13]. This evidence concerns the gene STAT3 and cancer.