After the baseline characteristics have been recorded, an ultrasound examination will be carried out (the upper zone of Fig. 1) to determine whether there is current bile duct and/or liver pathology. Patients with liver mass or bile duct dilatation will be directed to confirmatory diagnostic tests and, if CCA is confirmed, they will be transferred to the patient cohort (the lower zone of Fig. 1).The patient cohort will include all CCA patients diagnosed in the region over a 5year duration, with an estimated number of 5000 histologically proven new cases per year or 25,000 in the fiveyear recruitment period. It will include individuals diagnosed from the screening cohort, as well as new patients diagnosed at the nine tertiarycare hospitals participating in the CASCAP study. After diagnosis, the treatment regime will be determined and recorded. These patients will be treated according to the routine care procedures of the hospitals. Followup treatment will be recorded. Patients will be followedup until the end of life.