ISG15 and intrahepatic cholangiocarcinoma: Given the limited sample size of intrahepatic cholangiocarcinoma in TCGA, we utilized cohort data from 244 patients with intrahepatic cholangiocarcinoma from the Zhongshan Hospital for prognostic analysis and validated a significant association of high ISG15 expression levels with poor prognosis in patients (p = 0.012) (Fig. 3D).