Tanaka M, et al. - In the present study, researchers examined the importance of ecotropic virus integration site 1 protein homolog (EVI1) in intrahepatic cholangiocarcinoma (ICC), which has been regarded as a heterogeneous group of cancers. Compared to EVI1-negative ICC, EVI1-positive ICC exhibited higher frequencies of aggressive pathological indicators like periductal infiltrative growth, hilar invasion, advanced UICC stage, major vascular invasion, and perineural invasion. In all resected cases and in curative resected cases, patients with EVI1-positive ICC demonstrated worse overall survival and recurrence-free survival. Findings revealed that EVI1-positive ICC is an aggressive ICC displaying both large-duct and/or gastric phenotypes. Therefore, a transcriptional factor EVI1 is related to aggressive behavior in ICC and can be a therapeutic target molecule. On the other hand, EVI1 might be a key molecule for the development of intraductal papillary neoplasms of the bile duct.