MLH1 and colorectal cancer: CIMP represents a distinct form of epigenetic instability in colorectal cancer, [3, 21, 35–37] causing most sporadic colorectal cancers with microsatellite instability (MSI) through the epigenetic inactivation of MLH1. However, no study has reported the epigenetic alterations, including CIMP status, associated with rectal carcinoid tumors.