NRG1 and cholangiocarcinoma: Although rare (estimated in ~0.2% of all solid tumors) NRG1 fusions have been identified in several GI malignancies, including pancreatic ductal adenocarcinoma (~0.5%) (particularly in KRAS wild-type tumors), cholangiocarcinoma (~0.5%), and CRC (~0.1%) [133,134,135].