title: Adenomas with high-grade dysplasia and early adenocarcinoma are more likely to be sessile in the proximal colon.
abstract: OBJECTIVE
  Size and the sessile morphology of an adenoma may explain why colonoscopy is less effective in preventing proximal colonic cancer than distal cancers. We wanted to determine if advanced polypoid neoplasms (APNs, i.e. adenoma with high-grade dysplasia or early adenocarcinoma) are more likely to be sessile and/or smaller in the proximal colon.
  
  
  METHODS
  We searched our institution's pathology database from 2004 to 2012 and identified patients with APNs. Polyps were categorized by size, morphology and location in the colon. Average polyp size and morphology were determined for each location.
  
  
  RESULTS
  During the study period, 564 patients with APNs were identified. Of these, adenocarcinoma was noted in 21.6% and high-grade dysplasia in 78.4%. The average patient age was 64.4 years and 54.9% were men. The proportion of APNs that were ≤ 5 mm was 1.7%, ≤ 10 mm 19.3% and ≤ 15 mm 39%. APNs in the proximal colon were larger than those in the distal colon, but the difference was not statistically significant (27 vs 24 mm; P = 0.06). Eighty-three per cent of APNs in the proximal colon were sessile vs 57% in the distal colon (P = 0.001). APNs in the proximal colon were almost four times more likely to be sessile than in the distal colon (OR = 3.7). A similar association was noted for polyps ≤ 20 mm or polyps with high-grade dysplasia.
  
  
  CONCLUSIONS
  APNs in the proximal colon were almost four-times more likely to be sessile than those in the distal colon. No difference in the size of polyps was noted.
authors.affiliation: Division of Gastroenterology, Beth Israel Deaconess Medical and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Sawhney
authors.affiliation: Division of Gastroenterology, Beth Israel Deaconess Medical and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: J
authors.initials: J
authors.lastname: Dickstein
authors.affiliation: Division of Gastroenterology, Beth Israel Deaconess Medical and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: J
authors.initials: J
authors.lastname: LeClair
authors.affiliation: Division of Gastroenterology, Beth Israel Deaconess Medical and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: C
authors.initials: C
authors.lastname: Lembo
authors.affiliation: Pathology, Beth Israel Deaconess Medical and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: E
authors.initials: E
authors.lastname: Yee
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000236:Adenoma / Q000473:pathology*; D000368:Aged; D003106:Colon; D003110:Colonic Neoplasms / Q000473:pathology*; D003111:Colonic Polyps / Q000473:pathology*; D003113:Colonoscopy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D047368:Tumor Burden
keywords: Polyps; adenoma; colon cancer; colonoscopy