Mutations in the proto-oncogene KRAS (Kirsten rat sarcoma virus) are frequently reported in CCA, as well as alterations of the p53 gene and CDKN2A (cyclin-dependent kinase inhibitor 2A gene), being more prevalent in eCCA than in iCCA [56,59] (Figure 3). Here, CDKN2A is linked to cholangiocarcinoma.