Sa1396 NEXT-GENERATION SEQUENCING OF PANCREATIC CYST FLUID IS BOTH SENSITIVE AND SPECIFIC FOR THE CLASSIFICATION OF NEOPLASTIC CYSTS AND THE DETECTION OF ADVANCED NEOPLASIA IN INTRADUCTAL PAPILLARY MUCINOUS NEOPLASMS: A PROSPECTIVE MULTI-INSTITUTIONAL STUDY

Next-generation sequencing (NGS) of pancreatic cyst fluid (PCF) is a useful adjunct to the identification of neoplastic pancreatic cysts. The detection of KRAS, GNAS and/or RNF43 mutations are specific for mucinous pancreatic cysts, such as intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs). Additional alterations in TP53, SMAD4 and the mTOR genes are associated with advanced neoplasia. In contrast, serous cystadenomas (SCAs) harbor VHL alterations and cystic pancreatic neuroendocrine tumors (PanNETs) have MEN1 and/or chromosomal copy number alterations (CNAs). While previous reports have proven the efficacy of NGS testing, these studies are largely retrospective, utilizing postoperative PCF, employing insensitive detection techniques and single institutional experiences. Therefore, we performed a prospective multi-institutional study to evaluate the accuracy of NGS testing in pancreatic cyst classification and the detection of advanced neoplasia. Within a 14-month period, 875 PCFs were collected by EUS-FNA from several institutions and prospectively tested using an NGS panel of 22 pancreatic cyst-associated genes. Molecular findings were correlated with carcinoembryonic antigen (CEA), cytology results and diagnostic pathology. Among 875 specimens, 849 (97%) PCFs were satisfactory for NGS testing. Mutations in KRAS/ GNAS/RNF43 were detected in 474 (56%) cases and correlated with elevated CEA (>192ng/mL) and mucin by cytology (p<0.001). Additional alterations in TP53/SMAD4/mTOR were identified in 63 (7%) PCFs and associated with malignant cytology (p<0.001). Mutations in VHL and MEN1/CNAs were also seen in 64 (8%) and 42 (5%) cases, respectively. Diagnostic pathology was available for 117 (14%) patients and included: 54 IPMNs with 26 harboring advanced neoplasia, 3 low-grade MCNs, 48 cystic PanNETs, 5 SCAs and 7 non-neoplastic cysts. The sensitivity and specificity of KRAS/GNAS/RNF43 mutations for IPMNs/MCNs was 93% and 100%, respectively. In conjunction with these mutations, alterations in TP53/SMAD4/mTOR had 96% sensitivity and 100% specificity for IPMNs with advanced neoplasia. In contrast, the sensitivities and specificities of main duct dilatation, an EUS mural nodule and malignant cytology were 42% and 76%, 31% and 93%, and 46% and 100%, respectively. Among cystic PanNETs, mutations in MEN1/CNAs had a 77% sensitivity and a 100% specificity. While limited in number, VHL mutations were associated with a sensitivity and specificity of 100% for SCAs. Finally, all 7 non-neoplastic cysts were devoid of any genomic alterations. NGS testing of PCF is highly sensitive and specific for mucinous pancreatic cysts, especially IPMNs, advanced neoplasia in an IPMN, and SCAs. Further, the identification of mutations in MEN1/CNAs represent a promising marker for cystic PanNETs.