S-1 monotherapy in a patient with cholangiolocellular carcinoma: A case report.

A 71-year-old man with alcoholic cirrhosis was found to have multiple hypervascular lesions in the liver on enhanced computed tomography. An ultrasound-guided biopsy of the lesion was performed. Immunohistochemical analysis for hepatocyte paraffin 1 expression was negative; cytokeratin (CK) 7, CK19, epithelial cell adhesion molecule and epithelial membrane antigens were positive; mucicarmine staining was negative. The tumor was thus histologically diagnosed as cholangiolocellular carcinoma (CoCC). The tumor was inoperable due to the associated advanced liver disease. In addition, the patient preferred systemic chemotherapy using only orally administered agents. Thus, S-1 monotherapy was recommended. S-1 was initially administered orally at a dose of 80 mg/day. Although the levels of tumor marker (prothrombin induced by vitamin K absence/antagonist-II and carbohydrate antigen 19-9) levels were marginally elevated, their values did not change over the entire course. The patient achieved a partial response according to the Response Evaluation Criteria In Solid Tumors (RECIST) and modified RECIST 1 year after chemotherapy initiation. In conclusion, S-1 monotherapy exhibited promising efficacy against unresectable CoCC.