Cancers of the bile duct and the pancreas are virtually indistinguishable using conventional histopathological and clinical characteristics. We sought to utilize microRNA (miR) profiling to differentiate these two cancers.

RNA was harvested from the tumors of patients undergoing curative resection for cholangiocarcinoma (n=75) or pancreatic adenocarcinoma (n=20) and compared with adjacent normal bile duct or pancreas, respectively. Differential microRNA expression profiles were determined using NanoString® technology.

41 differentially expressed miRs were identified in cholangiocarcinoma (25 overexpressed, 16 underexpressed) and 52 miRs were found in pancreatic adenocarcinoma (30 overexpressed, 22 underexpressed) relative to adjacent normal tissue. Of these two profiles, 15 miRs were commonly dysregulated between tumor types. Eight miRs were similarly over- or underexpressed in cholangiocarcinoma and pancreatic adenocarcinoma whereas the other seven miRs had inverse expression levels.

Cholangiocarcinoma has a distinct miR profile from pancreatic adenocarcinoma. Discrimination between these two tumor types may be possible with as few as seven miRs.