title: Patients With Nonpolypoid (Flat and Depressed) Colorectal Neoplasms at Increased Risk for Advanced Neoplasias, Compared With Patients With Polypoid Neoplasms.
abstract: Nonpolypoid colorectal neoplasms (NP-CRNs) are more likely to contain high-grade dysplasia or early-stage cancer than polypoid neoplasms. We aimed to determine the long-term outcomes of patients with at least 1 NP-CRN.
  
  
  
  We performed a longitudinal cohort study of 4454 patients at a Veterans' Affairs hospital who underwent colonoscopy from 2000 through 2005; 341 were found to have 1 or more NP-CRNs and were matched (3:1) with patients found to have 1 or more polypoid neoplasms (controls, n = 1025). We collected and analyzed data on baseline colonoscopy findings and first follow-up colonoscopy results through August 2014. We calculated the incidence of advanced neoplasia at first follow-up colonoscopy, as defined by the presence of ≥1 tubular or sessile serrated adenomas ≥10 mm in diameter, tubulovillous adenoma, high-grade dysplasia, or invasive cancer.
  
  
  
  A significantly higher proportion of patients with 1 or more NP-CRNs (16.0%) were found to have advanced neoplasia at their first follow-up colonoscopy than controls (8.6%); the adjusted risk ratio was 1.6 (95% confidence interval, 1.05-2.6; P = .03). A significantly higher proportion of patients with 1 or more NP-CRNs were found to have additional NP-CRNs at the follow-up colonoscopy (17%) than controls (7%; relative risk, 2.3; 95% confidence interval, 1.5-3.5; P < .001). Similar proportions of patients in each group developed cancers after colonoscopy.
  
  
  
  In a longitudinal cohort study, we found that patients with NP-CRN were more likely to develop additional NP-CRNs and to have advanced neoplasms at their first follow-up colonoscopy than patients with only polypoid neoplasms. However, patients with NP-CRN were not more likely to develop cancers after colonoscopy when surveillance guidelines were followed. Larger studies are needed to determine risk of colorectal cancer in patients with NP-CRN.
authors.affiliation: Veterans Affairs Palo Alto Health Care System, Palo Alto, California; Stanford University School of Medicine, Stanford, California; University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina.
authors.forename: Sarah K
authors.initials: SK
authors.lastname: McGill
authors.affiliation: Veterans Affairs Palo Alto Health Care System, Palo Alto, California; Stanford University School of Medicine, Stanford, California.
authors.forename: Roy
authors.initials: R
authors.lastname: Soetikno
authors.affiliation: Veterans Affairs Palo Alto Health Care System, Palo Alto, California; Stanford University School of Medicine, Stanford, California.
authors.forename: Robert V
authors.initials: RV
authors.lastname: Rouse
authors.affiliation: Veterans Affairs Palo Alto Health Care System, Palo Alto, California.
authors.forename: Hobart
authors.initials: H
authors.lastname: Lai
authors.affiliation: Veterans Affairs Palo Alto Health Care System, Palo Alto, California; Stanford University School of Medicine, Stanford, California. Electronic address: endoresection@me.com.
authors.forename: Tonya
authors.initials: T
authors.lastname: Kaltenbach
mesh_terms: D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011127:Polyps / Q000473:pathology*
keywords: Colon Cancer; Endoscopy; Progression; Risk Factors; Screening