Su1405 Clinical Utility of Intracystic DNA (PathFinder TG) in Very Small Pancreatic Cysts

Abstract

Su1405 Clinical Utility of Intracystic DNA (PathFinder TG) in Very Small Pancreatic Cysts David H. Robbins, Christine Yu, Gregory B. Haber, David Hudesman Gastroenterology, Lenox Hill, New York, NY; Medicine, Beth Israel, New York, NY Background: The management of incidental pancreatic cysts less than 20mm is a common clinical conundrum. Small cysts are generally thought to be benign, even when mucinous, but little is known about the malignant potential of such lesions (i.e., even aggressive pathobiology starts out as a small cyst). The value added in sampling such small undifferentiated cysts must be weighed against the risks, costs, and utility of pursuing additional information or surveillance at an “early stage.” The dilemma is compounded by limited non-operative diagnostics as small lesions do not often yield sufficient fluid at EUS-FNA for standard assays such as CEA. Definitive surgical pathology is rarely pursued in this population. DNA analysis, which can be performed with very small amounts of intracystic fluid, may be a promising approach to identify high-risk lesions by detecting adverse molecular fingerprints at an early stage. The impact of size and the frequency of adverse DNA mutations has not been well studied in very small pancreatic cysts. Objective: We sought to better characterize the relationship between size and frequency of genetic mutations when applied to pancreatic cysts less than or equal to 20mm. SettingMulti-center study, retrospective. Methods: Two high-volume referral centers specializing in EUS-FNA were included in the study. Information was collected on patients who underwent EUS-guided FNA for evaluation of pancreatic cysts less than or equal to 20mm as measured by EUS. 168 patients underwent DNA analysis, these were classified by size and confirmatory surgical pathology where available. Cyst size was not included in the PathFinder TG assay requisition in the vast majority of cases (the lab was blinded to cyst size). Results: 64 RedPath analyses were performed on distinct pancreatic cysts less than or equal to 20mm in diameter. Conclusion: DNA analysis was feasible in 94% (60/64) of all cysts less than 20mm, indeterminant results included those with insufficient fluid quality or degraded DNA (lack of signal). Two cases (3%) were characterized as HGD and/or adenocarcinoma, both in the 0-1cm group. These preliminary findings suggest the utility for DNA analysis in very small cysts is low, but adverse molecular changes can be observed in a very small fraction. Whether or not size can be used as a cut-off in the decision to sample small cysts remains unclear and warrants further study.