title: Can quantification of faecal occult blood predetermine the need for colonoscopy in patients at risk for non-syndromic familial colorectal cancer?
abstract: BACKGROUND
  Patients at risk for non-syndromic (Lynch or polyposis) familial colorectal neoplasia undergo colonoscopic surveillance at intervals determined by clinically ascertained protocols. The quantitative immunochemical faecal occult blood test for human haemoglobin is specific and sensitive for significant colorectal neoplasia (cancer or advanced adenomatous polyp).
  
  
  OBJECTIVE
  To determine immunochemical faecal occult blood test efficacy for identifying significant neoplasia in at-risk patients undergoing elective colonoscopy.
  
  
  METHODS
  We retrospectively identified consecutive at-risk patients who provided three immunochemical faecal occult blood tests before colonoscopy. Quantitative haemoglobin analysis was performed by the OC-MICRO automated instrument using the 100 ng Hb/mL threshold to determine positivity.
  
  
  RESULTS
  In 252 at-risk patients undergoing colonoscopy; five had cancer, 14 an advanced adenoma and 46 a non-advanced adenoma. The immunochemical faecal occult blood test was positive in 31 patients (12.3%). Sensitivity, specificity, positive and negative predictive values for cancer were: 100%, 90%, 16% and 100%, and for all significant neoplasia: 74%, 93%, 45% and 98%. With 88% fewer colonoscopies, all colorectal cancers and 74% of all significant neoplasia would have been identified by this one-time immunochemical faecal occult blood test screening.
  
  
  CONCLUSIONS
  A sensitive, non-invasive, interval screening test might be useful to predetermine the need for colonoscopy in this at-risk population and minimize unnecessary examinations. This favourable retrospective evaluation will be extended to a prospective study.
authors.affiliation: Gastroenterology Department, Rabin Medical Center, Beilinson Hospital, Petach Tikva, Israel.
authors.forename: Z
authors.initials: Z
authors.lastname: Levi
authors.forename: P
authors.initials: P
authors.lastname: Rozen
authors.forename: R
authors.initials: R
authors.lastname: Hazazi
authors.forename: A
authors.initials: A
authors.lastname: Vilkin
authors.forename: A
authors.initials: A
authors.lastname: Waked
authors.forename: E
authors.initials: E
authors.lastname: Maoz
authors.forename: S
authors.initials: S
authors.lastname: Birkenfeld
authors.forename: Y
authors.initials: Y
authors.lastname: Niv
mesh_terms: D000368:Aged; D003113:Colonoscopy / Q000706:statistics & numerical data*; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D009780:Occult Blood; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment
chemical_list: D006454:Hemoglobins