title: Serum IgG4 elevation in pancreatic cancer: diagnostic and prognostic significance and association with autoimmune pancreatitis.
abstract: OBJECTIVE
  Serum IgG4 (sIgG4) elevation, more common to autoimmune pancreatitis (AIP), occurs in some patients with pancreatic cancer (PaC). We investigated whether sIgG4 could differentiate AIP from PaC, its role in prognostication, and the concomitant occurrence of AIP and PaC.
  
  
  METHODS
  We identified all patients with PaC (n = 548) and with type 1 AIP (n = 99) with sIgG4 measurements from 2001 to 2011. We compared demographics and sIgG4 profiles in these groups. Among patients with PaC, we compared resectability and mortality with and without elevated sIgG4. We reviewed AIP and PaC tissue specimens to identify concomitant occurrence of both diseases.
  
  
  RESULTS
  Patients with AIP were more likely to have elevation in sIgG4 (65% vs 10.4%, P < 0.001) and sIgG4 more than 2 times upper limit of normal (40% vs 2.4%, P < 0.001). Patients with PaC with sIgG4 elevation were more commonly male compared with those with normal sIgG4 (81% vs 53%). Both groups were similarly aged with similar rates of resectability and mortality. No evidence of concurrent PaC and AIP was found.
  
  
  CONCLUSIONS
  Mild elevations in sIgG4 cannot distinguish AIP from PaC. Elevations more than 2 times upper limit of normal appear more commonly in AIP. Serum IgG4 elevation has no prognostic significance in PaC. We could not identify a relationship between AIP and PaC.
authors.affiliation: From the Divisions of *Internal Medicine, †Gastroenterology and Hepatology, and ‡Laboratory Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Taiwo
authors.initials: T
authors.lastname: Ngwa
authors.forename: Ryan
authors.initials: R
authors.lastname: Law
authors.forename: Phil
authors.initials: P
authors.lastname: Hart
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Smyrk
authors.forename: Suresh T
authors.initials: ST
authors.lastname: Chari
mesh_terms: D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D010195:Pancreatitis / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D011379:Prognosis
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G