# A case of perihilar cholangiocarcinoma with peritoneal dissemination that achieved a pathological complete response using immune checkpoint inhibitors: A case report

## TL;DR

A rare case of advanced perihilar cholangiocarcinoma with peritoneal spread achieved complete response after immune checkpoint inhibitors and surgery.

## Contribution

Demonstrates a rare pathological complete response in peritoneal-disseminated cholangiocarcinoma using ICIs and conversion surgery.

## Key findings

- Combination of GC and durvalumab led to a complete pathological response in advanced perihilar cholangiocarcinoma.
- Conversion surgery was feasible after achieving complete response in a case with peritoneal dissemination.
- This case suggests ICIs may offer curative potential in advanced BTC previously thought untreatable.

## Abstract

Surgical resection is considered the only potentially curative treatment for biliary tract cancer (BTC). However, for patients with locally advanced or metastatic BTC, systemic chemotherapy remains the primary therapeutic option. Historically, chemotherapies such as gemcitabine plus cisplatin (GC), gemcitabine plus S-1, and GC plus S-1 have been employed; however, the prognosis remains poor. Recently, combined therapy with immune checkpoint inhibitors (ICIs) has emerged as a promising therapeutic approach for unresectable BTC. In cases with long-term efficacy to systemic chemotherapy, sequential surgical resection, known as conversion surgery, has also shown potential to improve overall outcomes in unresectable BTC. This case report presents a case of advanced perihilar cholangiocarcinoma with histologically confirmed peritoneal dissemination that achieved a pathological complete response after combination therapy with GC and durvalumab, followed by conversion surgery. Achieving a pathological complete response in the presence of peritoneal dissemination is rare. This case provides valuable insights into treatment strategies for this aggressive malignancy, demonstrating that a pathological complete response is possible even in the presence of peritoneal dissemination.