title: High prevalence of sessile serrated adenomas with BRAF mutations: a prospective study of patients undergoing colonoscopy.
abstract: OBJECTIVE
  Sporadic colorectal cancers with a high degree of microsatellite instability are a clinically distinct subgroup with a high incidence of BRAF mutation and are widely considered to develop from serrated polyps. Previous studies of serrated polyps have been highly selected and largely retrospective. This prospective study examined the prevalence of sessile serrated adenomas and determined the incidence of BRAF and K-ras mutations in different types of polyps.
  
  
  METHODS
  An unselected consecutive series of 190 patients underwent magnifying chromoendoscopy. Polyp location, size, and histologic classification were recorded. All polyps were screened for BRAF V600E and K-ras codon 12 and 13 mutations.
  
  
  RESULTS
  Polyps were detected in 72% of patients. Most (60%) were adenomas (tubular adenomas, tubulovillous adenomas), followed by hyperplastic polyps (29%), sessile serrated adenomas (SSAs; 9%), traditional serrated adenomas (0.7%), and mixed polyps (1.7%). Adenomas were more prevalent in the proximal colon (73%), as were SSAs (75%), which tended to be large (64% >5 mm). The presence of at least one SSA was associated with increased polyp burden (5.0 vs 2.5; P < .0001) and female sex (P < .05). BRAF mutation was rare in adenomas (1/248 [0.4%]) but common in SSAs (78%), traditional serrated adenomas (66%), mixed polyps (57%), and microvesicular hyperplastic polyps (70%). K-ras mutations were significantly associated with goblet cell hyperplastic polyps and tubulovillous adenomas (P < .001).
  
  
  CONCLUSIONS
  The prevalence of SSAs is approximately 9% in patients undergoing colonoscopy. They are associated with BRAF mutation, proximal location, female sex, and presence of multiple polyps. These findings emphasize the importance of identifying and removing these lesions for endoscopic prevention of colorectal cancer.
authors.affiliation: Conjoint Gastroenterology Laboratory, Queensland Institute of Medical Research, Herston, Brisbane, Australia.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Spring
authors.forename: Zhen Zhen
authors.initials: ZZ
authors.lastname: Zhao
authors.forename: Rozemary
authors.initials: R
authors.lastname: Karamatic
authors.forename: Michael D
authors.initials: MD
authors.lastname: Walsh
authors.forename: Vicki L J
authors.initials: VL
authors.lastname: Whitehall
authors.forename: Tanya
authors.initials: T
authors.lastname: Pike
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Simms
authors.forename: Joanne
authors.initials: J
authors.lastname: Young
authors.forename: Michael
authors.initials: M
authors.lastname: James
authors.forename: Grant W
authors.initials: GW
authors.lastname: Montgomery
authors.forename: Mark
authors.initials: M
authors.lastname: Appleyard
authors.forename: David
authors.initials: D
authors.lastname: Hewett
authors.forename: Kazutomo
authors.initials: K
authors.lastname: Togashi
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Jass
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Leggett
mesh_terms: D000236:Adenoma / Q000235:genetics* / Q000473:pathology; D003110:Colonic Neoplasms / Q000235:genetics* / Q000473:pathology; D003111:Colonic Polyps / Q000235:genetics / Q000473:pathology; D003113:Colonoscopy; D005260:Female; D011905:Genes, ras; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011446:Prospective Studies; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D051153:Wnt Proteins / Q000502:physiology
chemical_list: D051153:Wnt Proteins; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf