[A Case of Curative Surgery for Locally Advanced Small Bowel GIST after Imatinib Therapy].

According to the risk classification of recurrence, the standard treatment for gastrointestinal stromal tumor(GIST)is complete surgical resection and postoperative adjuvant therapy with imatinib; however, the usefulness of neoadjuvant therapy is unclear. We report a case of giant GIST in the pelvis suspectedly having bladder infiltration that was radically resected and underwent preoperative imatinib therapy. A 52-year-old man visited a clinic because of abdominal pain, fever, and frequent urination. An abdominal mass was determined, and the patient was referred to our hospital for detailed examination and treatment. Contrast-enhanced CT revealed a 17 cm diameter irregular mass from the lower navel to the pelvis, and the bladder boundary was partially unclear. Transrectal biopsy was performed using endoscopic ultrasonography, and according to the Fletcher classification, a high-risk GIST was diagnosed. After preoperative imatinib therapy of 400 mg/day was administered for 3 months, surgery was performed. The tumor was strongly adhered to the bladder, but no invasion was observed, and partial small intestine resection was performed. The surgical margin was negative without capsule damage. On day 34 postoperatively, imatinib therapy was resumed, and as of 1 year postoperatively, the course is well without recurrence.