Acinar Cell Carcinoma of the Pancreas Successfully Controlled by IRIS: A Case Report and Literature Review

Acinar cell carcinoma (ACC) of the pancreas is a rare pancreatic tumor with poor prognosis. We present the first case of ACC of the pancreas successfully controlled by S-1 combined with a colorectal regimen. A 49-year-old Japanese female was referred to our clinic for right upper quadrant pain. Imaging studies demonstrated 2 solid tumors under the pancreas, and pancreatoduodenectomy with tumor resection was performed. Based on pathologic examination, the diagnosis of ACC of the pancreas was made according to the World Health Organization criteria. Eleven months after surgery, lymph node recurrence with elevations in serum concentrations of carbohydrate antigens (CA) 19-9 and CA125 were recognized. Treatments with carboplatin combined with paclitaxel, docetaxel, and gemcitabine, respectively, were attempted; however, there were no significant responses to these regimens. After starting S-1/irinotecan combination chemotherapy (IRIS), the concentrations of the tumor markers declined, accompanied by a reduction in tumor size. Because S-1 is an oral anticancer agent used on an outpatient basis with a low incidence of side effects, we believe that S-1-based chemotherapy is a strong candidate for the first-line treatment of recurrent or unresectable ACC.