Post-operative Surveillance and Management of Intrahepatic Cholangiocarcinoma Using Circulating Tumor DNA: A Case Report.

Cholangiocarcinomas (CCAs) are a subclass of biliary tract tumors that arise from the epithelial lining of bile ducts. They are subdivided broadly into intra- and extrahepatic CCA, with extrahepatic being the more common. Circulating tumor DNA (ctDNA) is a form of liquid biopsy obtained from dying tumor cells in the peripheral blood. Assays may be tumor-informed or tumor-agnostic, with the former requiring tissue sampling to evaluate detectable mutations present in an individual patient's tumor. Here we present a case of intrahepatic CCA managed with hepatectomy followed by adjuvant chemotherapy, with subsequent surveillance and management guided by tumor-informed ctDNA. A 79-year-old female presented to our hospital in December 2019 with three months of postprandial epigastric abdominal pain. Computed tomography (CT) revealed a 5.7 x 5.2 cm left hepatic lobe mass, and surgical pathology confirmed invasive CCA. She underwent left hepatectomy with hepaticojejunostomy one month after presentation and started adjuvant chemotherapy thereafter. She followed us to our cancer center for standard surveillance along with ctDNA. Her tumor markers were within normal limits, and ctDNA was negative until May 2022, when ctDNA was detected, while CA 19-9 remained normal; CT imaging was without evidence of disease. Positron emission tomography-computed tomography (PET-CT) performed in July 2022 revealed local recurrence at the surgical margin, which was confirmed by an endoscopic biopsy. She began gemcitabine-capecitabine chemotherapy in October 2022, completed four cycles followed by chemoradiation therapy, and is currently at her baseline functional status with no detectable radiologic or molecular evidence of disease.