No validated biomarkers exist that can identify patients with biliary tract cancer at an early stage or predict treatment outcomes. The objective of the present study is to find diagnostic, prognostic and predictive biomarkers.

Biliary tract cancer (BTC) is a heterogeneous disease and includes both gallbladder cancer and cholangiocarcinoma. Combined BTC is the fifth most common gastrointestinal cancer. The prognosis is poor with a median overall survival of less than a year and estimated 5-year survival of about 20 % for all stages. The poor survival is related to aggressive malign nature, late diagnosis, and limited treatment options. Today, only CA 19-9 is used in routine practice but its use as a prognostic or diagnostic biomarker is very limited.

The objective of the present study is to find diagnostic, prognostic, and predictive biomarkers, which can be used to 1) diagnose BTC early in the disease course with high specificity and sensitivity, 2) improve prognostication, or 3) predict and monitor treatment effectiveness and tolerability for the individual patient.

CHOCA is an observational and translational open cohort study with a prospective collection of biological materials (blood samples and tissue) and clinical data in patients with BTC receiving standard or protocolized treatment. Blood samples (i.e. serum, EDTA plasma and buffy coat, and blood in PAXgeneRNA tubes) are collected from all patients before operation or start of chemotherapy and during treatment with blood sampling before the 2nd cycle of chemotherapy and longitudinally at the time of follow-up CT scan (about every 3 months) until disease progression. Tissue removed during routine diagnostic procedures or treatment will be requisitioned.

The patients are followed until death. The following data are collected: Demographics, disease characteristics, comorbidities and lifestyle factors, routine blood tests (i.e. hematology, creatinine, liver enzymes, bilirubin, carbohydrate antigen 19-9, C-reactive protein); type of operation; types of chemotherapy, reason for termination of therapy; date of disease recurrence in operated patients; date of disease progression for each line of chemotherapy; and date of death. Biomarker analyses will include a range of molecules with different characteristics such as DNA, Single Nucleotide Polymorphism (SNPs), RNA, microRNA, proteins, proteoglycans, and metabolites. Controls will be included from other studies in order to identify potential diagnostic biomarkers,. Controls include patients with other diseases or healthy subjects. Biomarkers will be analyzed using appropriate methods and statistical analysis following REMARK guidelines.

Inclusion Criteria:

• Histological or cytological diagnosis of BTC
• Patients referred for treatment of BTC
• Signed informed consent

Exclusion Criteria:

• None

The study will include patients with BTC referred for oncological treatment (adjuvant, neoadjuvant, or palliative setting [any treatment line]) at the Department of Oncology, Herlev & Gentofte Hospital, Denmark and patients referred for surgery at Rigshospitalet (Denmark). The two sites are responsible for all treatment of BTC in eastern Denmark, a region with a population of almost 2.7 million.