Types IIa, LST-G and LST-F flat adenomas all contained significantly fewer APC mutations compared to polypoid adenomas (IIa: 29.6% (8/27), LST-G: 25% (3/12), LST-F: 34.4% (11/32) vs polypoid 55.6% (45/81) p = 0.02, 0.05 and 0.04, respectively). Here, APC is linked to adenoma.