Conversion Surgery after Complete Response to Immune Checkpoint Inhibitor-Based Sequential Chemotherapy for Initially Unresectable Perihilar Cholangiocarcinoma: A Case Report.

INTRODUCTION

Perihilar cholangiocarcinoma (PHCC) is often diagnosed at an advanced stage, and surgical resection is frequently precluded due to local progression, distant metastases, or insufficient liver remnant function. Although systemic chemotherapy has recently improved outcomes in unresectable biliary tract cancer, reports of conversion surgery after achieving pathological complete response (pCR) remain extremely rare, thus the role of salvage surgery remains unclear.

CASE PRESENTATION: A woman in her 50s presented with abdominal distension and jaundice. Imaging revealed a bile duct stricture below the hepatic duct confluence with a 30-mm pericholedochal lymph node invading the hepatic arteries and portal vein bifurcation. Cytology confirmed adenocarcinoma, and she was diagnosed with unresectable PHCC (Bismuth type II, UICC T4N1M0, stage IIIC). First-line gemcitabine, cisplatin, and S-1 (GCS) chemotherapy was given for 8 courses, resulting in marked lymph node shrinkage, though vascular involvement persisted. Due to adverse events, the regimen was switched to gemcitabine, cisplatin, and durvalumab (GCD) for 7 courses, which maintained disease control. After 13 months of sequential chemotherapy, hepatic functional reserve was adequate, and left portal vein reconstruction with hepatic artery preservation was feasible. Conversion surgery consisting of right hemihepatectomy with portal vein resection/reconstruction and extrahepatic bile duct resection was performed. Pathology showed no residual tumor cells and extensive fibrosis with chronic inflammation, confirming a pCR. The patient has been receiving adjuvant S-1 and remains disease-free 4 months postoperatively.

CONCLUSIONS

This case demonstrates that sequential chemotherapy-specifically GCS followed by GCD-can enable conversion surgery and possibly achieve pCR in initially unresectable PHCC. The case highlights the potential of sequential chemotherapy to expand curative options for this otherwise highly lethal disease.