PTGS2 and colorectal carcinoma: Similar to this pattern of over-expression, Qi-Bing et al [50] in their large-sized study of 1,026 CRC cases in China, showed that the proportions of well, moderate and poorly differentiated CRC cases that over-expressed COX-2 are 73.5%, 80.8% and 74.5%, respectively, while the overall expression is 77.97% with no significant correlation with sex, age or tumour location but demonstrate a significant correlation with tumour size ≥5 cm, serosa invasion, late stage and distant metastasis.