title: Prevalence of different subtypes of serrated polyps and risk of synchronous advanced colorectal neoplasia in average-risk population undergoing first-time colonoscopy.
abstract: OBJECTIVE
  A growing body of evidence indicates that patients with sessile serrated adenoma/polyp (SSA/P) and traditional serrated adenoma (TSA) are at risk for subsequent malignancy. Despite increasing knowledge on histological categorization of serrated polyps (SPs) data are lacking on the actual prevalence and the association of each SP subtype with advanced colorectal neoplasia.
  
  
  METHODS
  We prospectively determined the prevalence of different SP subtypes and evaluate the association with synchronous advanced neoplasia in asymptomatic average-risk subjects undergoing first-time colonoscopy. All retrieved polyps were examined by two independent pathologists. Serrated lesions were classified into hyperplastic polyps (HP), SSA/P (without and with cytological dysplasia, SSA/P/DIS), and TSA, and were screened for BRAF and K-ras mutations.
  
  
  RESULTS
  Among 258 polyps detected in 985 subjects, the proportion of SSA/P and TSA was 8.9% and 1.9% with an overall prevalence of 2.3% and 0.6%, respectively. SSA/Ps were small without significant difference in their location between proximal and distal colon; TSA were predominantly left-sided. BRAF mutation was common in SSA/Ps and K-ras mutation was present in all TSA. Independent predictors of advanced neoplasia were male sex (odds ratio (OR)=2.0, 95% confidence interval (CI) 1.0-4.0), increasing age (OR=4.5, 95% CI 1.5-13.4 for 50-69 years and OR=9.9, 95% CI 3.1-31.5 for >70 years), current smoking (OR=2.0, 95% CI 1.3-6.8), >3 tubular adenoma (OR=3.6, 95% CI 1.9-6.4), and SSA/P (OR=6.0, 95% CI 1.9-19.5).
  
  
  CONCLUSIONS
  The substantial prevalence of BRAF-mutated SSA/P and the independent association with synchronous advanced colorectal neoplasia in asymptomatic average-risk subjects support the overall impact of the serrated pathway on colorectal cancer (CRC) risk in general population. The endoscopic characteristics of SSA/P emphasize the need of high-quality colonoscopy as a key factor for an effective CRC screening program.
authors.affiliation: 1] University of Bristol, School of Clinical Sciences, Bristol, UK [2] University of Padova, Surgical and Gastroenterological Sciences, Padova, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Buda
authors.forename: Manuela
authors.initials: M
authors.lastname: De Bona
authors.forename: Isabella
authors.initials: I
authors.lastname: Dotti
authors.forename: Pierluca
authors.initials: P
authors.lastname: Piselli
authors.forename: Eva
authors.initials: E
authors.lastname: Zabeo
authors.forename: Renzo
authors.initials: R
authors.lastname: Barbazza
authors.forename: Angelo
authors.initials: A
authors.lastname: Bellumat
authors.forename: Flavio
authors.initials: F
authors.lastname: Valiante
authors.forename: Ermanno
authors.initials: E
authors.lastname: Nardon
authors.forename: Chris S
authors.initials: CS
authors.lastname: Probert
authors.forename: Massimo
authors.initials: M
authors.lastname: Pignatelli
authors.forename: Giorgio
authors.initials: G
authors.lastname: Stanta
authors.forename: Giacomo Carlo
authors.initials: GC
authors.lastname: Sturniolo
authors.forename: Michele
authors.initials: M
authors.lastname: De Boni