PTGS2 and gastric cancer: The overexpression of COX-2 and COX-2 mRNA is not limited just to colon cancer but can be considered as a common feature in many solid tumors (head and neck squamous cell carcinomas, mesothelioma, hepatocellular carcinoma, gastric cancer, breast cancer and non-small cell lung carcinoma) [9,10,11,12,13,14].