title: Chromogranin A measurement in metastatic well-differentiated gastroenteropancreatic neuroendocrine carcinoma: screening for false positives and a prospective follow-up study.
abstract: BACKGROUND
  Multiple causes of false-positive chromogranin A (CgA) measurement have been reported that may affect its impact as a surrogate marker of RECIST progression in well-differentiated gastroenteropancreatic neuroendocrine tumors (WDGEPNET). ?
  
  
  OBJECTIVE
  1) To evaluate the frequency of false-positive CgA results. 2) To prospectively compare CgA variations with RECIST morphological changes in patients without known causes of false-positive CgA measurements.?
  
  
  METHODS
  First, the conditions responsible for potentially false-positive CgA measurements were screened in 184 consecutive patients with metastatic WDGEPNET. Secondly, a variation in CgA at a 6-month interval was compared to RECIST results at 6 months in 46 patients.?
  
  
  RESULTS
  Among 184 patients, elevated CgA was found in 130 cases (71%) including 99 patients with at least one cause of a false-positive result. Impaired kidney function as well as medication with proton pump inhibitors were found to be the 2 major causes of false-positive results. The sensitivity and specificity of CgA measurements compared with morphological tumor changes according to the RECIST criteria were 71% and 50%, respectively, at 6 months.?
  
  
  CONCLUSIONS
  Routine screening for the causes of false-positive CgA measurements is mandatory in WDGEPNET patients. Our study does not validate the use of CgA as a surrogate marker of tumor progression.
authors.affiliation: Institut Gustave Roussy, Villejuif - France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Vezzosi
authors.forename: Thomas
authors.initials: T
authors.lastname: Walter
authors.forename: Agnès
authors.initials: A
authors.lastname: Laplanche
authors.forename: Jean Luc
authors.initials: JL
authors.lastname: Raoul
authors.forename: Clarisse
authors.initials: C
authors.lastname: Dromain
authors.forename: Philippe
authors.initials: P
authors.lastname: Ruszniewski
authors.forename: Michèle
authors.initials: M
authors.lastname: d'Herbomez
authors.forename: Joël
authors.initials: J
authors.lastname: Guigay
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mitry
authors.forename: Guillaume
authors.initials: G
authors.lastname: Cadiot
authors.forename: Sophie
authors.initials: S
authors.lastname: Leboulleux
authors.forename: Catherine
authors.initials: C
authors.lastname: Lombard-Bohas
authors.forename: Françoise
authors.initials: F
authors.lastname: Borson-Chazot
authors.forename: Michel
authors.initials: M
authors.lastname: Ducreux
authors.forename: Eric
authors.initials: E
authors.lastname: Baudin
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D018278:Carcinoma, Neuroendocrine / Q000097:blood / Q000556:secondary*; D053379:Chromogranin A / Q000097:blood*; D005189:False Positive Reactions; D005260:Female; D005500:Follow-Up Studies; D005770:Gastrointestinal Neoplasms / Q000097:blood / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D010190:Pancreatic Neoplasms / Q000097:blood / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D053379:Chromogranin A