KRAS and adenocarcinoma: KRAS mutations were found to be more frequent in non-adenocarcinoma (43.56% vs. 32.30%, P = 0.005), right colon (42.04% vs. 32.09%, P = 0.009), well and moderately differentiated tumors (36.86% vs. 22.31%, P=0.003), positive CEA (39.76% vs. 32.05%, P = 0.033), and positive CA19-9 (44.78% vs. 32.78%, P = 0.006).