On the other hand, since chronic inflammation has been recognized as an important risk factor for the development of GI tumors, the underlying molecular mechanisms have been studied extensively. Chronic inflammation may induce cell mutations and promote malignant transformation in normal cells of the GI mucosa. The inflammatory reaction generated during carcinogenesis involves the formation of reactive oxygen and nitrogen species (ROS and RNS) derived from mononuclear phagocytes and lymphocytes, as well as the development of immune response, and the production of pro-inflammatory cytokines. Nuclear factor-κB (NF-κB) is considered as the main mediator of the immune response. The activation of NF-κB through phosphorylation leads to translocation of NF-κB in the nucleus, where regulates the transcription of several pro-inflammatory cytokines and chemokines. Furthermore, chronic inflammation can create the appropriate conditions for genomic and epigenetic changes.