title: Prevalence and distinctive biologic features of flat colorectal adenomas in a North American population.
abstract: OBJECTIVE
  To assess the prevalence of flat and depressed (F&D) colorectal adenomas in the United States, we performed a prospective study of 211 American patients.
  
  
  METHODS
  Dye-assisted colonoscopy was performed in the presence of both an American and a Japanese investigator.
  
  
  RESULTS
  F&D lesions were found in 22.7% of patients, and these were more likely to be adenomatous than polypoid lesions (82% vs. 67%; P = 0.03) and contained more invasive cancer (4.5% vs. 0%; P = 0.04), which also appeared to be at a disproportionately advanced stage. The average size of all F&D advanced lesions (high-grade dysplasia and cancer) was significantly smaller than comparable polypoid lesions (10.75 +/- 2.7 mm vs. 20 +/- 2.9 mm; P < 0.05). F&D adenomas showed significantly stronger fragile histidine triad (FHIT) expression and lower p53 reactivity than similarly sized polypoid adenomas, whereas proliferative and apoptotic indices were similar in both groups.
  
  
  CONCLUSIONS
  We conclude that there is a significant prevalence of colonic F&D colorectal adenomas in this country and that these lesions have significantly different biologic features than polypoid lesions. The clinical and epidemiologic implications of these findings for American patients need to be addressed in further studies.
authors.affiliation: Third Department of Internal Medicine, Asahikawa Medical College, Asahikawa, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Saitoh
authors.forename: I
authors.initials: I
authors.lastname: Waxman
authors.forename: A B
authors.initials: AB
authors.lastname: West
authors.forename: N K
authors.initials: NK
authors.lastname: Popnikolov
authors.forename: Z
authors.initials: Z
authors.lastname: Gatalica
authors.forename: J
authors.initials: J
authors.lastname: Watari
authors.forename: T
authors.initials: T
authors.lastname: Obara
authors.forename: Y
authors.initials: Y
authors.lastname: Kohgo
authors.forename: P J
authors.initials: PJ
authors.lastname: Pasricha
mesh_terms: D017766:Acid Anhydride Hydrolases; D000236:Adenoma / Q000453:epidemiology / Q000473:pathology*; D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins; D009656:North America / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D011506:Proteins / Q000032:analysis; D019014:fas Receptor / Q000032:analysis; D000099170:Bis(5'-adenosyl)triphosphatase
chemical_list: D017766:Acid Anhydride Hydrolases; D009363:Neoplasm Proteins; D011506:Proteins; D019014:fas Receptor; D000099170:Bis(5'-adenosyl)triphosphatase