[Successful treatment of huge peritoneal metastasis from duodenal gastrointestinal stromal tumor resistant for imatinib mesylate].

Constitutive activation of KIT receptor tyrosine kinase is a critical factor in the pathogenesis of gastrointestinal stromal tumors. Imatinib mesylate (IM, Glivec), a selective tyrosine kinase inhibitor, has been shown in clinical studies to work against such tumors. But there is little information on whether combination of IM and surgical treatment can prolong survival in cases with unresectable multiple liver metastases. We report a case of successful treatment of huge peritoneal metastasis from duodenal gastrointestinal stromal tumor resistant for IM. Therefore, we discuss some important implications. This 41-year-old Japanese man underwent a pancreaticoduodenectomy for GIST of the duodenum in January 2003. The postoperative course was good at first, but 3 months after the initial operation, MRI showed multiple liver metastases. The patient was treated with 400 mg of IM once daily with only weak liver dysfunction as a side effect. The initial response to treatment of CR continued for 20 months. Then huge mass of rt. abdomen appeared and gradually increased in size. Examination revealed that this mass is recurrent of peritoneal metastasis of the GIST. Extirpation was performed and this huge mass was recurrent GIST from omentum. Currently, IM is the first-line therapy for non-resectable GISTs, but a single agent therapy often leads to tumor resistance. IM-resistant GIST are treated with combination of novel molecular targeted-drug, RF, TAE, however, the effect is not enough. Surgical treatment is one of the successful treatments of huge peritoneal metastasis from duodenal gastrointestinal stromal tumor resistant for IM. Further examination in more cases of recurrent GIST is also necessary to estimate the effectiveness of treatment with IM.