Pathological complete response after chemotherapy in initially unresectable distal cholangiocarcinoma

Surgical resection is the only curative treatment for cholangiocarcinoma, but it is often diagnosed at advanced stages, making surgical resection infeasible. Recently, the concept of conversion surgery has expanded the indications for surgical treatment, thanks to advancements in both perioperative management and chemotherapy. However, it remains unclear which patients benefit most from this treatment strategy. We present a case of initially unresectable cholangiocarcinoma in which a pathologic complete response was achieved following chemotherapy. A man in his seventies presented with jaundice and was referred to our hospital. Abdominal computed tomography revealed dilation of the intrahepatic bile ducts and thickening of the common bile duct, suggestive of distal cholangiocarcinoma. The tumor was initially unresectable due to metastatic para-aortic lymph nodes, and chemotherapy with gemcitabine and cisplatin was initiated. After six courses of chemotherapy, the lymph nodes showed a partial response, and tumor markers returned to normal levels. However, further chemotherapy was intolerable due to thrombocytopenia. Our cancer board then decided to perform a pancreaticoduodenectomy. Pathologic examination of the resected specimen showed complete disappearance of the primary tumor, but viable cancer cells were found in the resected lymph nodes. Seven months post-surgery, recurrence in the para-aortic nodes was detected through imaging and elevated tumor markers. Despite this, the patient remains alive 16 months post-surgery with normal tumor marker levels, following additional chemotherapy. Pathologic complete response of the primary tumor is rarely observed in patients with initially unresectable distal cholangiocarcinoma, and a multidisciplinary approach, including conversion surgery, may be effective in such cases.