PTGS2 and colorectal carcinoma: The rate of COX-2 over-expression increases during the course of CRC development from adenoma to CRC in situ to invasive CRC, thus recapitulating events in the adenoma-carcinoma progression.18 It may, therefore, imply that COX-2 over-expression may be a marker of the progression of CRCs from adenomas.18 However, studies on COX-2 and its antagonists in colorectal adenomas are limited in Africa, as most studies are from Asia and Western countries.