Accuracy of Endoscopic Ultrasound, Fine Needle Aspiration, Cytology, and Cyst Fluid Tumor Markers in Patients with Pancreatic Cystic Lesions: Comparison with Surgical Pathology and 12-month Follow-up

Abstract

Background: Preoperative differentiation of pancreatic cystic lesions (PCL) remains difficult despite improvement in imaging modalities and cystic fluid analysis. The aim of this study was to assess the diagnostic accuracy of endoscopic ultrasonography (EUS) and fine needle aspiration (FNA) with tumor marker measurement in the diagnosis of PCLs. Methods: The records of 56 consecutive patients with PCLs referred to a gastroenterologist and pancreatic surgeon were reviewed. The mean age was 60.4 yrs and 66% were female. Eighteen percent had a history of pancreatitis and 59% had symptoms of abdominal pain. The mean cyst size was 20mm; 7% were <1cm and 21% were >5cm. Cyst location was the head or uncinate in 38%. EUS was performed in 30 (54%). FNA was performed in 46 (82%) of them. The results of EUS, cytology, carcinoembryonic antigen (CEA) and carbohydrate antigen (CA 19-9) levels were compared with the final diagnosis. Based on surgical pathology and/or an imaging follow-up of at least 12 mos, cysts were classified as benign (simple cysts, pseudocyst, serous cystadenoma) or malignant/potentially malignant (mucinous cystadenoma, solid-pseudopapillary tumors, cystic adenocarcinomas). Receiver-operator curve (ROC) analysis was used to determine ideal cutoffs for the cyst tumor markers. Results: Final diagnosis was obtained in 41 (89%) of 46 cases; 23 (50%) had surgery. Sensitivity, specificity and positive and negative predictive value of EUS (without FNA) to distinguish benign from malignant/premalignant PCL were 50%, 56%, 36% and 69% and for cytology were 71%, 96%, 92% and 82%, respectively. CA 19-9 >37 U/ml had a 70% sensitivity and 90% specificity, whereas CEA >3.1 ng/ml had a 70% sensitivity and 85% specificity. High levels of CEA (>100ng/ml were never seen in benign lesions: 100% specific). Areas under the curve for cytology and tumor markers were similar (0.78-0.83). Conclusion: Tumor marker analysis of fluid retrievable by EUS with FNA was found to be a very useful tool in distinguishing benign from malignant/premalignant PCL and similar in performance to cytology.