Next‐generation sequencing in the evaluation of biliary strictures in patients with primary sclerosing cholangitis

Abstract

Background Primary sclerosing cholangitis (PSC) is a well‐described risk factor for the development of cholangiocarcinoma (CCA). Early detection of CCA in these patients is of great importance because it expands options for therapeutic interventions, including liver transplantation. Current diagnostic tests for the evaluation of biliary strictures are limited to biliary brushing (BB) cytology and fluorescence in situ hybridization (FISH). Next‐generation sequencing (NGS) has become an important diagnostic tool in oncology and may be a useful tool for diagnosing CCA on BBs. It is not clear how NGS performs when it is added to BB cytology and FISH in patients with PSC. Methods This study reports the authors' experience with NGS performed as a prospective cotest with cytology and FISH on BBs obtained from 60 patients with PSC followed at Massachusetts General Hospital. A duct with malignancy was defined as a high‐risk (HR) stricture with either high‐grade dysplasia or CCA. Results NGS was better than FISH and cytology in detecting HR strictures, which showed multiple genetic mutations in all cases. NGS provided specific mutational information, and NGS results were reproducible in longitudinal samples. Conclusions Adding NGS to BB cytology and FISH in the evaluation of biliary strictures for patients with PSC may provide additional information that could help to inform clinical management.

Significance of KRAS mutation testing in biliary brushing cytology specimens: A 10‐year retrospective review

“…Previous studies suggest that KRAS mutation testing in bile duct brushing is a useful ancillary test. 13,19,24,28 A recent NGS study demonstrated that KRAS mutation is the most prevalent genetic mutation among biliary strictures in patients with primary sclerosing cholangitis. 19 Sturm et al 24 studied 312 consecutive patients with extrahepatic biliary stenosis and found that conventional cytology combined with KRAS mutational analysis was more sensitive than conventional cytology alone.…”

“…In the current study, we retrospectively reviewed a cohort of 269 patients with biliary tract stricture and investigated the correlation between their biliary duct brushing cytology, KRAS mutation, and histopathological/clinical follow‐ups. We observed a relatively low mutation rate (19%), moderate sensitivity (36%) but high specificity (92%) of KRAS mutation analysis in detecting malignant biliary strictures, which is consistent with previous reports 19,24,39 . In contrast, KRAS mutation testing in pancreatic FNA biopsy was reported to have overall sensitivity and specificity of 79% and 100%, respectively 34,38 .…”

“…The value of KRAS mutational analysis in bile duct stricture cytology samples still needs to be fully validated. Previous studies suggest that KRAS mutation testing in bile duct brushing is a useful ancillary test 13,19,24,28 . A recent NGS study demonstrated that KRAS mutation is the most prevalent genetic mutation among biliary strictures in patients with primary sclerosing cholangitis 19 .…”

“…[13][14][15][16][17][18][19] Among these attempts, next-generation sequencing (NGS) seemed to be better than fluorescence in situ hybridization and cytology in detecting high-risk strictures because of showing multiple genetic mutations with good reproducibility in longitudinal samples. 19 KRAS mutation is one of the most common genetic alterations in human cancers and is commonly seen in tumors causing biliary stenosis (ie, pancreatic carcinoma and bile duct carcinoma). [20][21][22] More than 95% of the KRAS mutations in these neoplasms occur in codons 12 and 13, which makes their detection relatively easy.…”

“…This reported low sensitivity has led to the impression that bile duct brushing by cytomorphology may not be a useful diagnostic methodology. In the past few decades, several approaches have been developed to enhance the cytological analysis of bile duct brushing specimens, including improvement of brushing techniques, intraductal ultrasound examination, digital image analysis, protocols for onsite cytopathologic examination following inconclusive or indeterminate brushing specimens, immunolabeling, fluorescence in situ hybridization, genetic analysis for neoplasia‐specific genes, and sequential mutational analysis 13‐19 . Among these attempts, next‐generation sequencing (NGS) seemed to be better than fluorescence in situ hybridization and cytology in detecting high‐risk strictures because of showing multiple genetic mutations with good reproducibility in longitudinal samples 19 …”