Comparison of carcinoembryonic antigen and molecular analysis in pancreatic cyst fluid.

Background: Pancreatic-cyst fluid carcinoembryonic antigen (CEA) levels and molecular analysis are useful diagnostic tests in differentiating mucinous from nonmucinous cysts.

Objective: To assess agreement between CEA and molecular analysis for differentiating mucinous from nonmucinous cysts.

Design: Retrospective analysis.

Setting: Academic medical center.

Methods: Patients who underwent EUS-guided FNA for evaluation of pancreatic cysts were identified. The following information was used to designate a cyst mucinous: the CEA criterion was CEA level >or=192 ng/mL and the molecular analysis criteria were DNA quantity >or=40 ng/microL and/or k-ras 2-point mutation and/or >or=2 allelic imbalance mutations. Pathologic analysis of cysts served as the criterion standard.

Results: From 2006 to 2007, 100 patients met the study criteria. The average age of the patients was 63 years, 65% were women, and 30% were symptomatic. The mean diameter of pancreatic cysts was 2.5 cm. The median CEA value was 83 ng/mL (range 1-50,000 ng/mL), the mean DNA content was 16 ng/microL (range 1-212 ng/microL), 11% had K-ras mutations, and 43% had >or=2 allelic imbalance mutations. When using prespecified criteria, there was poor agreement between CEA and molecular analysis for the classification of mucinous cysts (kappa = 0.2). Poor agreement existed between CEA and DNA quantity (Spearman correlation = 0.2; P = .1), K-ras mutation (kappa = 0.3), and >or=2 allelic imbalance mutations (kappa = 0.1). Of the 19 patients for whom a final pathologic diagnosis was available, CEA had a sensitivity of 82% compared with 77% for molecular analysis. When CEA and molecular analysis were combined, 100% sensitivity was achieved.

Limitations: Retrospective analysis and small sample size.

Conclusion: There was poor agreement between CEA levels and molecular analysis for diagnosis of mucinous cysts. Diagnostic sensitivity was improved when results of CEA levels and molecular analysis were combined.