Role of adjuvant and neoadjuvant therapy for resectable biliary tract cancer.

: Although the safety of biliary tract cancer resection has improved over the years, the recurrence rate is still high, and the postoperative prognosis remains low after biliary tract cancer resection. Therefore, the development of effective adjuvant therapy is essential to improve treatment outcomes. Because biliary tract cancer is rare compared with other gastrointestinal cancers, there have been only a small number of clinical trials of adjuvant therapy. However, in recent years, the results of several large-scale randomized controlled trials have been published, and clinical trials investigating the efficacy of new regimens are currently ongoing.: This review presents the results of previously published important phase II and III clinical trials of adjuvant and neoadjuvant therapy for biliary tract cancer and discusses their interpretation. The future direction of new research on resectable biliary tract cancer treatment is also discussed.: The foundations of large-scale clinical trials of adjuvant and neoadjuvant therapy for biliary tract cancer are underway, and new trials will establish evidence of their effectiveness. Additionally, breakthroughs in treatment through genetic and molecular research are expected.