Adult Age Distribution Aged Aged, 80 and over Bile Duct Neoplasms--mortality Cholangiocarcinoma--mortality Combined Modality Therapy Confidence Intervals Disease Progression Female Follow-Up Studies Hepatectomy--methods Hepatic Duct, Common--surgery Humans Klatskin Tumor--mortality Male Middle Aged Probability Prospective Studies Reference Values Risk Assessment Sex Distribution Survival Analysis Treatment Outcome