title: Fecal immunochemical testing results and characteristics of colonic lesions.
abstract: OBJECTIVE
  Fecal immunochemical tests (FIT) are used to detect blood in feces, which might indicate the presence of colorectal neoplasia. The aim of this study was to investigate whether FIT results vary depending on the characteristics of colonic lesions.
  
  
  METHODS
  This was a retrospective analysis of lesions detected in a cohort of asymptomatic individuals (aged 50 - 75 years) who were invited to participate in a FIT-based screening pilot in The Netherlands. The mean FIT result was compared across subgroups of individuals defined by histopathology of the most advanced lesion detected. In addition, the results were compared with data from a primary colonoscopy screening trial, in which participants also completed a FIT.
  
  
  RESULTS
  In three rounds of FIT-based screening, a total of 877 FIT-positive individuals underwent colonoscopy. Higher mean FIT results (hemoglobin [Hb]/g feces) were observed in individuals with carcinomas (199 μg Hb/g) and advanced adenomas (87 μg Hb/g) compared with participants with nonadvanced adenomas (50 μg Hb/g) or those with serrated lesions (46 μg Hb/g) (P < 0.001). In the primary colonoscopy trial, 1256 participants completed a FIT test and underwent colonoscopy. The number of participants with nonadvanced adenomas as the most advanced lesion was comparable between this group and the FIT-based screening group (20 % vs. 22 %).
  
  
  CONCLUSIONS
  In FIT-based screening, the mean FIT results varied depending on the characteristics of the most advanced colonic lesion. The proportion of participants with a nonadvanced adenoma as the most advanced lesion was similar in the FIT-based screening group and in the primary colonoscopy screening group, suggesting that these lesions are coincidental findings rather than FIT-detected findings.
  
  
  BACKGROUND
  www.trialregister.nl number NTR2755.
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Sascha C
authors.initials: SC
authors.lastname: van Doorn
authors.affiliation: Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Inge
authors.initials: I
authors.lastname: Stegeman
authors.affiliation: Department of Clinical Chemistry, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: An K
authors.initials: AK
authors.lastname: Stroobants
authors.affiliation: Department of Gastroenterology and Hepatology, Flevoziekenhuis Almere, The Netherlands.
authors.forename: Marco W
authors.initials: MW
authors.lastname: Mundt
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: de Wijkerslooth
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Fockens
authors.affiliation: Department of Gastroenterology and Hepatology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Ernst J
authors.initials: EJ
authors.lastname: Kuipers
authors.affiliation: Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Bossuyt
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Evelien
authors.initials: E
authors.lastname: Dekker
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000473:pathology*; D000236:Adenoma / Q000175:diagnosis / Q000473:pathology*; D000328:Adult; D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000473:pathology*; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009780:Occult Blood; D010865:Pilot Projects; D012189:Retrospective Studies