ERBB2 and biliary tract neoplasm: A genetic study of 186 patients with PSC-biliary tract cancer showed eCCA with high genomic alterations in TP53 (35.5%), KRAS (28.0%), CDKN2A (14.5%), and SMAD4 (11.3%), and even in underlying druggable mutation genes, such as HER2/ERBB2 [32].