The efficacy of bile liquid biopsy in the diagnosis and treatment of biliary tract cancer

Abstract Background Diagnosing biliary tract cancer is difficult because endoscopic retrograde cholangiopancreatography (ERCP) is performed fluoroscopically, and the sensitivity of bile cytology is low. Liquid biopsy of bile using targeted sequencing is expected to improve diagnosis and treatment, but few studies have been conducted. In this study, we examined whether liquid biopsy of bile improves the diagnostic sensitivity of biliary strictures. Methods A total of 72 patients with biliary strictures who underwent ERCP at Chiba University Hospital between April 2018 and March 2021 were examined. Of these, 43 and 29 were clinically and pathologically diagnosed as having malignant and benign biliary strictures, respectively. We performed targeted sequencing of bile obtained from these patients, and the sensitivity of this method was compared with that of bile cytology. Detection of at least one oncogenic mutation was defined as having malignancy. Results The sensitivity of bile cytology was 27.9%, whereas that of genomic analysis was 46.5%. Comparing bile cytology alone with the combination of cytology and genomic analysis, the latter was more sensitive (53.5%, p < .001). Among the 43 patients with malignant biliary strictures, mutations with FDA‐approved drugs were detected in 11 (26%). Conclusions Liquid biopsy of bile can potentially diagnose malignancy and detect therapeutic targets.