KRAS and adenoma: Recent, well-conducted studies based on extensive case series – carried out after the recognition of serrated adenomas – have repeatedly found that KRAS mutations are rare in tubular adenomas, which constitute 85–90% of colorectal non-serrated adenomas.27,28 Barry et al.28 documented a 3% frequency of KRAS mutations in a prospective study of 303 adenomas, most mutations being observed in sessile and tubulovillous adenomas.