DNA Methylation Alterations In Endoscopic Retrograde Cholangiopancreatography Brush Samples of Patients With Suspected Pancreaticobiliary Disease

Abstract

Molecular markers of pancreatic neoplasia could aid in the evaluation of suspicious pancreatic lesions where cytology is nondiagnostic. We evaluated the utility of detecting and measuring aberrantly methylated DNA as markers of pancreatic and other periampullary cancers. Methylation analysis was performed on endoscopically obtained brush samples from the biliary and pancreatic ducts from 130 individuals with biliary tract strictures: 41 with pancreatic ductal adenocarcinoma, 10 with biliary tract cancers, 13 with other periampullary neoplasms, and 66 with non-neoplastic strictures including 27 with primary sclerosing cholangitis and 39 with other benign strictures. Brush DNA concentrations of methylated Cyclin D2, NPTX2, and TFPI2 promoter DNA were measured by real-time quantitative methylation-specific polymerase chain reaction (QMSP). Conventional MSP was also performed with a 5-gene panel. QMSP could accurately distinguish patients with pancreatic cancer and other periampullary cancers from those with benign periampullary disease; 73.2% of patients with pancreatic ductal adenocarcinoma had at least 1 gene positive for methylation by QMSP (defined as > or =1% TFPI-2 DNA and > or =3% methylated NPTX2 and Cyclin D2 DNA) in their brush samples, compared with 80% of patients with a biliary tract cancer and only 13.6% of patients with a benign stricture (P < .001). Cytology had 19.5% sensitivity and 100% specificity. QMSP had significantly better overall diagnostic accuracy than both cytology and MSP. The detection and quantification of aberrantly methylated DNA in endoscopic brush samples are a promising tool to differentiate benign from malignant biliary strictures.