A comparative analysis of K-ras mutation and carcinoembryonic antigen in pancreatic cyst fluid.

Background/aims: Analysis of cystic fluid may be useful in distinguishing between benign and malignant cysts which has significant impact on their management. The aim of our study was to assess the diagnostic utility of carcinoembryonic antigen (CEA) and K-ras gene mutation in pancreatic cysts fluid.

Methods: The study included 56 patients with pancreatic cystic fluid collected for analysis. The cysts were classified as benign (simple cysts, pseudocysts, serous cystadenoma) - 39 patients or premalignant/malignant (mucinous cystadenoma, IPMN, cystadenocarcinoma) - 17 patients. The patients history, CEA fluid concentrations and presence of K-ras mutation were analyzed.

Results: CEA were higher in patients with malignant cysts (mean levels 238 ± 12.5 ng/ml; range 32.8-4985 ng/ml) compared to benign lesions (mean levels 34.5 ± 3.7 ng/ml; range 3.9-693 ng/ml; p < 0.001). K-ras mutation correctly classified 11 of 17 patients with premalignant/malignant lesions. It was also detected in 1 patient with final diagnosis of benign cyst (the sensitivity 64.7% and the specificity 97.4%; p < 0.01). If CEA and molecular analysis were combined in that cysts with either CEA level>45 ng/ml or presence of K-ras mutation, than 16 of 17 premalignant/malignant cysts were correctly identified (94.1%).

Conclusion: Molecular analysis of pancreatic cyst fluid adds diagnostic value to the preoperative diagnosis and should be considered when cyst cytologic examination is negative for malignancy.