Comparison of KRAS Mutation Analysis and FISH for Detecting Pancreatobiliary Tract Cancer in Cytology Specimens Collected During Endoscopic Retrograde Cholangiopancreatography

Abstract

Pancreatobiliary tract strictures result either from malignancies of the biliary tract and pancreas or from nonmalignant etiopathogenesis. The goal of this study was to determine whether KRAS mutations could be identified in residual pancreatobiliary stricture brushings and to compare the performance characteristics of KRAS mutation analysis to cytology and fluorescence in situ hybridization (FISH) for the detection of carcinoma. Residual brushing cytology cell pellets were retrieved from 132 patients with subsequent clinicopathologic follow-up of cholangiocarcinoma (n ‫؍‬ 41), pancreatic adenocarcinoma (n ‫؍‬ 35), gallbladder cancer (n ‫؍‬ 2), and nonmalignant strictures (n ‫؍‬ 54). All specimens had a prior cytology and FISH UroVysion results as part of clinical practice. KRAS mutation analysis was performed using the quantitative PCR DxS KRAS Mutation Test Kit. KRAS mutation analysis was successful in 130 of 132 specimens. KRAS mutations and polysomic (ie, positive) FISH results were identified in 24 (69%) and 22 (63%) pancreatic adenocarcinoma specimens, respectively, with a combined sensitivity of 86% (30/35). KRAS mutations and polysomic FISH results were identified in 12 (29%) and 17 (41%) cholangiocarcinoma specimens, with a combined sensitivity of 54% (22/41). KRAS mutations were identified in two patients with primary sclerosing cholangitis, and benign follow-up. Residual cytology specimens can be used to detect KRAS mutations by quantitative PCR. Combined KRAS mutation and FISH analysis appear to increase the cancer detection rate in patients with pancreatobiliary strictures.

EUS-FNA with rescue fluorescence in situ hybridization for the diagnosis of pancreatic carcinoma in patients with inconclusive on-site cytopathology results

“…10,11 If other molecular and cytologic techniques such as K-ras mutation analysis and digital image analysis are combined with FISH and cytology, accuracy also may improve, as demonstrated in patients with pancreaticobiliary strictures. 6,12 Molecular tests applied to EUS-FNA samples is a novel, exciting field that will help improve accuracy in the diagnosis of pancreatic cancer. There are a few molecular and cytologic techniques already available to be performed in FNA specimens, but studies are preliminary.…”

Recall processes for biliary cytology in primary sclerosing cholangitis

“…The addition of other targets to biliary cytology and FISH specimens would also be another method to enhance CCA detection. For example, utilizing a cohort of PSC and non-PSC patients, the addition of Kirsten rat sarcoma viral oncogene homolog mutation testing by quantitative PCR to routine cytology specimens improved the sensitivity for CCA detection to 54% when combined with polysomy [24]. Indeed, there have been a variety of specific genetic alterations associated with CCA.…”

Endoscopic diagnosis of biliary tract disease

“…Other diagnostic modalities, such as DNA ploidy analysis [37,38], mutational analysis [42,43,44 & ], and mucin expression pattern analysis [45][46][47] have been investigated as potential further tools in the assessment of possible pancreaticobiliary malignancies, but have not as yet gained wide clinical usage. Recently, bile proteomics have been used to identify disease-specific peptide patterns in bile aspirates, discriminating between benign and malignant pancreaticobiliary disease with an accuracy of around 90% [48 & ].…”