Abstract 51P
Background
Despite multiple investigations, upto 20% of biliary strictures remain indeterminate. Several recent studies have implicated Extracellular Vesicles (EVs) as potential biomarkers in various cancers. The aim of this study is to evaluate the accuracy of bile EV sizes and concentrations in differentiating malignant from benign biliary stenoses (BS).
Methods
35 patients (20 malignant,15 benign) undergoing ERCP for biliary obstruction were prospectively enrolled at Asian Institute of Gastroenterology, India. Bile was collected upstream from the biliary obstruction before any contrast medium injection. Malignant group included pancreatobiliary cancers and diagnosis was confirmed by histopathological examination (HPE). Benign group included biliary obstruction due to CBD stones and benign biliary strictures. The benign biliary strictures needed a minimum follow up period of 1 year to rule out occult malignancy not apparent on initial evaluation. EV sizes and concentrations were determined by nanoparticle tracking analyses. Area under ROC curve (ROC-AUC) was used to determine a test’s discriminative capability.
Results
Bile EV sizes and concentrations were higher in malignant as compared to benign BS (p<0.05). A cut-off of 9.95×1014 nanoparticles/L in bile distinguished patients with malignant from benign etiologies with 100% accuracy in pancreatic cancer, cholangiocarcinoma and ampullary malignancies (ROC-AUC was 100%). Using the cut-off, it was possible to identify occult malignancies not apparent on either initial imaging or HPE, which were confirmed only during follow-up evaluation. However in patients with gall bladder (GB) cancers causing biliary stricture, bile EV concentrations performed poorly in differentiating malignant from benign BS (ROC-AUC was 50%). Bile from CBD might not have been representative of GB tumor microenvironment and yield can probably be improved by cystic duct cannulation.
Conclusions
Concentration of EVs in bile samples discriminates between patients of malignant from benign biliary stenoses with 100% accuracy in pancreatic, bile duct and ampullary malignancies and might have a role in detecting occult malignancies not apparent on initial clinical, radiological or histopathological examination.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.