Bile ctDNA Genomic Profiling and Concordance With Tumor Tissue in Biliary Tract Cancer

This study is being done to find out whether bile fluid can be used to detect genetic changes in tumors of patients with advanced biliary tract cancer (BTC), such as cancer of the bile ducts or gallbladder. Currently, doctors often use a sample of tumor tissue to look for genetic changes that can help guide treatment decisions, including the use of targeted therapies. However, in biliary tract cancer, it can be difficult or risky to collect enough tumor tissue for this kind of testing. This study will collect a small amount of leftover bile (about 20 mL) during a procedure that patients are already having for medical reasons (such as endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic biliary drainage (PTBD), which are used to drain bile). A blood sample (about 20 mL) will also be collected at the same time patients are already having blood drawn as part of their regular care. No additional needle sticks or procedures will be done only for this study. Researchers will analyze the genetic material found in the bile and blood samples and compare the results with the genetic testing already done on the patient's tumor tissue. The main goal is to see how closely the genetic changes found in bile match those found in tumor tissue. The study will also look at whether bile testing can detect genetic changes that may help guide treatment, and whether these results are related to how patients respond to treatment and their long-term outcomes. About 100 patients with advanced biliary tract cancer will take part in this study at 4 hospitals in South Korea.