title: Non-polypoid colorectal neoplasms are relatively common worldwide.
abstract: Flat adenomas are found commonly at colonoscopy throughout the world. Similarly, small, flat submucosally invasive cancers have been described worldwide but are relatively rare, accounting for 5% to 10% of all cancers detected at colonoscopy. Although there appears to be no difference in frequency of non-polypoid colorectal neoplasms between East and West, considerable variation has been reported by individual studies, probably because of lack of consistency when defining a flat lesion. Flat elevated lesions are the most common type of flat lesion and do not appear to have a greatly increased risk of harboring invasive malignancy; however, flat lesions with depression have a significant risk of malignancy and are probably the precursor lesions for most small, flat, or ulcerating cancers.
authors.affiliation: Wolfson Unit for Endoscopy, Imperial College, St Mark's Hospital, Watford Road, Harrow, HA1 3UJ, London, UK.
authors.forename: Ana
authors.initials: A
authors.lastname: Ignjatovic
authors.forename: Brian P
authors.initials: BP
authors.lastname: Saunders
mesh_terms: D000236:Adenoma / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D003113:Colonoscopy / Q000379:methods; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D014943:Global Health; D006801:Humans; D015995:Prevalence; D012307:Risk Factors