MLH1 and adenoma: Compared with the control group (n = 2513), the Bethesda group was younger (P < 0.001), had a higher frequency of right colon cancer, synchronicity and metachronicity (all P < 0.001), a lower frequency of synchronous adenoma (P < 0.001), and higher rate of reduced expression of MMR protein (hMLH1 and hMSH2; both P < 0.001) and MSI-H (P < 0.001) (Table 2).