[A case of peritoneal dissemination of postoperative primary duodenal cancer successfully treated by TS-1 therapy].

A 62-year-old man reported to our hospital with serious complaints of abdominal pain, vomiting, and weight loss. An endoscopic examination detected a type 2 tumor of the descending limb of the duodenum. With a diagnosis of adenocarcinoma based on the biopsy finding, the patient was subjected to surgery. Laparotomy revealed the presence of a duodenal tumor disseminating to the omentum at the site where the transverse colon is attached. Pancreatoduodenectomy and partial resection of the transverse colon were carried out. CT conducted 6 months after surgery did not show any signs of tumor recurrence; but one year later, extensive tumor dissemination was noted on the hepatic surface. Upon consultation with the patient, a regimen of 80 mg/day of TS-1 given for 4 weeks followed by 2 weeks of a drug-free period was initiated. Six months later, the growth of tumor became arrested, improving his QOL. Nine months later, the tumor growth was progressive and the patient died two years after operation. The patient could gain long-term survival after operation. The TS-1 regimen applied in the present case may constitute a therapeutic strategy to be considered for similar conditions in future.