CTNNB1 and colorectal adenoma: Furthermore, the mutation frequency of CTNNB1 was low in adenomas (12.2%), a finding that is in accordance with most of the previous analyses on colorectal adenomas [26-28] and with the observation that CTNNB1 mutations mainly occur in hereditary nonpolyposis colorectal cancer [29] and in tumors exhibiting MSI [7,30].