Oxidative stress in ulcerative colitis-associated carcinogenesis.

Oxidative stress is defined as an imbalance between generation of reactive oxygen species (ROS) and decreased antioxidant defense systems. Oxidative stress develops particularly in inflammatory reactions because the inflammatory cells, neutrophils, and macrophages produce large amounts of ROS. It has been known for a long time that oxidative stress in inflamed tissue can pave the way for malignant tumors, and that it is a major pathogenetic factor for the well-established correlation between inflammatory diseases and cancer. Oxidative stress has long been associated with the pathogenesis of chronic inflammatory bowel disease (IBD)-related colorectal cancer. This article provides an overview of the pathology of ROS and presents recent advances concerning the role of ROS in IBD-related colorectal carcinogenesis (Fig. 1).