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 ≥192 ng/mL and the molecular analysis criteria were DNA quantity ≥40 ng/μL and/or k-ras 2-point mutation and/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/μL (range 1-212 ng/μL), 11% had K-ras mutations, and 43% had ≥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 ≥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.

Abbreviations: CEA, carcinoembryonic antigen, EUS-FNA, EUS-guided FNA