[A Case of Multiple Liver Metastases and Peritoneal Dissemination after Resection of a Gastrointestinal Stromal Tumor of the Stomach Successfully Treated with Imatinib Mesylate].

A 71-year-old man was diagnosed with a gastric tumor approximately 50mm in diameter on computed tomography (CT). In January 2000, he underwent a proximal gastrectomy. Pathological examination showed 5 mitoses per 50 high-power fields, while immunohistochemical analysis showed positive staining for KIT. Accordingly, the tumor was diagnosed as an intermediate- risk malignant gastrointestinal stromal tumor (GIST) for which the patient was followed. In January 2002, an abdominal CT scan revealed multiple hepatic tumors and a lower abdominal tumor, and the patient was diagnosed with liver metastases and peritoneal disseminations from GIST. After informed consent was provided, chemotherapy with 400 mg/day imatinib was initiated. The patient demonstrated a partial response 2 months after treatment. At 12 years 8 months after the diagnosis of liver metastasis and peritoneal disseminations, the patient shows no sign of recurrence.