PTGS2 and adenoma: In contrast to non-serrated adenomas [showing 2+ COX-2 in 28% (143/515) of cases], strong (2+) COX-2 expression was observed in none (0%) of 12 serrated lesions including 7 SSAs and 5 mixed polyps (p = 0.04) and in only 4.2% (1/24) of hyperplastic polyps (p = 0.008) (Table 1, Figure 3).