Validity of Carcinoembryonic Antigen and Carbohydrate Antigen 19-9 Measurements in Pancreatic Cyst Fluid with a Serum-Based Immunoassay

Abstract

To the Editor: Imaging techniques, cytology, and biochemical analysis [including carcinoembryonic antigen (CEA)1 and carbohydrate antigen 19-9 (CA 19-9) concentrations] of pancreatic cyst fluid obtained by endoscopic ultrasound-guided fine-needle aspiration are used to differentiate pancreatic cyst lesions, particularly those with malignant potential (1, 2). American College of Gastroenterology guidelines have outlined the published data relating to the diagnostic performance of pancreatic cyst fluid CEA and CA 19-9 (2) and concluded that cyst fluid CEA is the single most important factor in determining pancreatic cyst etiology. It is important, however, to appreciate that diagnostic cutoff values may be assay dependent. Many published reports do not describe the tumor marker assays used for analyzing pancreatic cyst fluid. In addition, the analytical validity of applying methods for serum tumor markers to the analysis of pancreatic cyst fluid does not appear to have been investigated in these studies. We investigated the analytical validity of the use of Roche E170 immunoassays for the measurement of CEA and CA 19-9 in pancreatic cyst fluid. We investigated pancreatic cyst fluid samples (n=21) obtained by ultrasound-guided …