Constant exposure to proinflammatory stimulus, whether it is infectious or non-infectious, is responsible for the overexpression of COX-2 and development of chronic inflammation, which might lead to malignancies, such as hepatitis virus infection-related hepatocellular carcinoma (Lu et al., 2015), reflux esophagitis-related esophageal cancer (Yang et al., 2012) and inflammatory bowel disease-related (IBD) colorectal cancer (Ullman and Itzkowitz, 2011). The gene discussed is PTGS2; the disease is colorectal cancer.