[Complete response achieved in a case of gastric gastrointestinal stromal tumor by administration of imatinib mesilate with concurrent relatively high-dose steroid therapy to control side effects].

We present a 53-year-old man who underwent proximal gastrectomy for gastric gastrointestinal stromal tumor (GIST) in August 2005. Imatinib mesilate (imatinib) 400 mg/day was started in February 2006 for left adrenal metastasis. Tumor size markedly decreased by April 2006, but medication had to be discontinued due to a pruritic rash. A distal pancreatectomy, splenectomy, and left adrenectomy were performed in August for recurrent adrenal metastases. Imatinib 200 mg/day started postoperatively was discontinued immediately due to fever and pruritus. Local recurrence with peritoneal dissemination was found in February 2007. Imatinib 100 mg/day with prednisolone (PDL) 5 mg/day was discontinued in two days due to pruritic dermatitis. Imatinib 200 mg/day with PDL 40 mg/day was restarted in April due to an increase in tumor size. Treatment continued without obvious side effects, and PDL dosage was tapered to 10 mg/day. The tumor was no longer visible on CT in May 2008, and complete response is being maintained as of August 2009.