Despite the fact that oncogenic mutations in CCA, such as TP53, KRAS, IDH1, ARID1A, and CDKN2A/B are commonly found in many other cancer types, it is apparent that the alteration frequencies differ substantially between intrahepatic CCA and extrahepatic CCA (eCCA) (Table 2). This evidence concerns the gene IDH1 and cholangiocarcinoma.