[Case of GIST of the rectum successfully treated with imatinib mesylate neoadjuvant therapy].

A 60-year-old man, with a high risk GIST of the rectum, suspected of the infiltration to the prostate and measuring 10 cm in diameter, underwent resection after neoadjuvant therapy of imatinib mesylate. Perineal approach was added because intraperitoneal dissection was not enough, however, the infiltration to the prostate was denied completely due to a reduction in the tumor size, thus total peritoneal resection was avoided. It seems that neoadjuvant therapy with imatinib mesylate is useful for resectability and for the preservation of the functions of ambient organs.