Inclusion Criteria:  Ages 20 and above. Pathological reported showed adenocarcinoma or adenosquamous carcinoma for patients with Biliary tract cancer (include intrahepatic cholangiocarcinoma (IHCC), extrahepatic cholangiocarcinoma (EHCC), gallbladder cancer (GBC) and ampulla of Vater cancer (AVC) ) or hepatocholangiocarcinoma. Willingness to provide the residual biopsy/operative slides. Life expectancy more than 3 months. Patients fully understand the protocol with the willingness to have regular follow-up. Patients are systemic treatment-naïve or under 1st line therapy  Exclusion Criteria:  Inability to cooperate by providing a complete medical history. No available tumor tissues for genetic testing. Undesirable compliance. Other malignancy within the past 1 years except adequately treated basal or squamous cell skin cancer or cervical cancer in situ.