PTGS2 and cancer: Multiple factors are involved in cancer-related inflammation such as cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6), and are also important for the epithelial–mesenchymal transition (EMT), which is a process whereby epithelial cells are decreased adhesion and enhanced migration or invasion to initiate cancer invasion and metastasis (Cao et al., 2015; West et al., 2015).