STAT3 and gastric cancer: TNF-α in the bloodstream may have oncogenic effects through several pathways, such as the stimulation of the production of reactive oxygen species (ROS), which can induce DNA damage and genomic instability; the stimulation of stem cell-like tumor progenitors by promoting β-catenin entry into the nucleus in inflammation-associated gastric cancer [31]; and the promotion of MMP expression, the invasiveness, and the survival of circulating metastatic seeds via NF-κB and STAT3 [32, 33].