[A case of a giant rectal gastrointestinal stromal tumor radically resectable after treatment with neoadjuvant imatinib mesylate].

A 64-year-old male patient was diagnosed with rectal gastrointestinal stromal tumor(GIST)by prostate biopsy, because of high PSA. We considered that a radical operation was impossible because the tumor occupied the pelvis, and we suspected prostate invasion. After neoadjuvant chemotherapy(imatinib mesylate 400 mg/day), the tumor size was reduced(90×85 mm→60×50mm), and we could thus perform radical resection. The patient is currently receiving adjuvant chemotherapy (imatinib mesylate 400 mg/day), without recurrence.