A Novel Technique of Spacer Implantation and Proton Beam Therapy for Hilar Cholangiocarcinoma:A Case Report

Wencui Yang^1*Junetsu Mizoe²

• ¹Xi'an International Medical Center Hospital, Xi’an, China
• ²Sapporo Kojinkai Memorial Hospital, Sapporo, Japan

The primary treatment for hilar cholangiocarcinoma is surgical resection. However, most patients have already lost the opportunity for surgical treatment at the time of initial diagnosis. Photon therapy (X-ray) has limited efficacy, while proton beam therapy (PBT) can improve local control. However, when the tumor is located near the gastrointestinal tract, the therapeutic effect remains limited. Space-making particle therapy (SMPT) has emerged as a strategy to address the clinical challenge of high-dose radiation exposure to nearby organs at risk (OARs). The technique involves the surgical implantation of a bioabsorbable spacer prior to the delivery of particle therapy. Therefore, we have been interested in the use of SMPT to preserve gastrointestinal tract. A 77-year-old man with hilar cholangiocarcinoma with placement of a bioabsorbable spacer and then received radical PBT of 72.6 Gy (relative biological effectiveness, RBE) in 22 fractions. Surgery was not part of the original treatment plan. However, approximately months after completing PBT, the patient developed biliary fluid accumulation which subsequently required surgical intervention. Notably, pathological examination of the resected irradiated field revealed a complete pathological response (pCR), providing direct evidence of the treatment's efficacy. This report describes one of the first cases in which a bioabsorbable spacer was surgically placed with the aim to preserve the gastrointestinal tract during PBT. SMPT is an innovative solution for hilar cholangiocarcinoma adjacent to gastrointestinal tract. This case demonstrated early feasibility and short-term efficacy of SMPT , but need long-time follow up.