title: The clinical utility and limitations of serum carbohydrate antigen (CA19-9) as a diagnostic tool for pancreatic cancer and cholangiocarcinoma.
abstract: BACKGROUND
  CA19-9 is a tumor marker for pancreatic cancer, cholangiocarcinoma, and other malignancies. However, its sensitivity and specificity is suboptimal in clinical practice, which we hypothesized limits its clinical utility.
  
  
  OBJECTIVE
  To evaluate the clinical utility and limitations of CA19-9 as a tumor marker.
  
  
  METHODS
  We performed a retrospective review of CA19-9 levels (U/ml) in 483 consecutive patients between 2006 and 2008 at two university hospitals. We abstracted clinical, radiographic, and pathological data and final diagnoses. Descriptive and non-parametric analyses were performed.
  
  
  RESULTS
  Patients presenting with jaundice had the highest CA19-9 (420) compared to other complaints (<20) (p<0.01). The indications with the highest CA19-9 had evidence of biliary obstruction (71), liver mass (54), and pancreatic head mass (27) compared to other indications (<15) (p<0.01). The diagnoses with the highest CA19-9 (p<0.01) were cholangiocarcinoma (476), pancreatic cancer (161), and choledocholithiasis (138). Using a receiver operator curve to evaluate CA19-9, the area under the curve was 0.7 when evaluating all patients for pancreatic cancer or cholangiocarcinoma or patients with pancreatic head mass for pancreatic cancer.
  
  
  CONCLUSIONS
  This study found that for pancreatic cancer and cholangiocarcinoma, CA19-9 had poor clinical utility as a tumor marker and did not change patient management. Elevations in CA19-9 were associated with biliary obstruction based on clinical history, laboratory data, and diagnoses.
authors.affiliation: Division of Gastroenterology and Hepatology, Stanford University, 300 Pasteur Dr., Always Building, Room M211, Stanford, CA 94305, USA. sundeeps@stanford.edu
authors.forename: Sundeep
authors.initials: S
authors.lastname: Singh
authors.forename: Shou-jiang
authors.initials: SJ
authors.lastname: Tang
authors.forename: Jayaprakash
authors.initials: J
authors.lastname: Sreenarasimhaiah
authors.forename: Luis F
authors.initials: LF
authors.lastname: Lara
authors.forename: Ali
authors.initials: A
authors.lastname: Siddiqui
mesh_terms: D000236:Adenoma / Q000175:diagnosis*; D001650:Bile Duct Neoplasms / Q000097:blood / Q000175:diagnosis*; D001653:Bile Ducts, Intrahepatic; D014408:Biomarkers, Tumor / Q000097:blood*; D018395:CA-19-9 Antigen / Q000097:blood*; D018281:Cholangiocarcinoma / Q000097:blood / Q000175:diagnosis*; D042883:Choledocholithiasis / Q000097:blood / Q000175:diagnosis; D002779:Cholestasis / Q000097:blood / Q000175:diagnosis; D005260:Female; D006801:Humans; D007565:Jaundice / Q000097:blood; D008297:Male; D010190:Pancreatic Neoplasms / Q000097:blood / Q000175:diagnosis*; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D018395:CA-19-9 Antigen