It is difficult to determine the reasons, but the possibilities may include racial factors, as most studies involve non-African subjects, genetic make-up – particularly COX-2 gene polymorphism, and the fact that most adenomas analysed in this current study were colonoscopic biopsies, which may not represent the entire tumour heterogeneity, even though the adenomas from three colectomy cases did not express COX-2 as well. Here, PTGS2 is linked to neoplasm.