Recent advances in radiation therapy for biliary tract cancer

Abstract

Radiation therapy (RT) plays an only limited role in the treatment of biliary tract cancer at present. Superiority of postoperative RT, or of palliative RT for unresectable cases, has not been shown compared to systemic therapy alone. In contrast, state-of-the-art RT is developing remarkably through technological innovation, including intensity-modulated RT (IMRT), stereotactic body RT (SBRT) and particle therapy (proton and heavy ion therapy). By using these novel RT, similar clinical outcomes have been reported compared to surgery in some other cancers than biliary tract cancer. The common feature of these novel RT is a high concentration of the RT dose, which means a dose escalation to the tumor without significantly increasing the dose to the normal liver tissue or the surrounding normal organs such as duodenum. Some clinical trials have already begun for biliary tract cancer using proton therapy or others. It is necessary to establish new evidence based on a combination of such novel RT and systemic therapy. For that purpose, mutual understanding and cooperation between surgical, medical, and radiation oncologists are of utmost importance.