[A Case of Rectal Gastrointestinal Stromal Tumor(GIST)Treated with Imatinib Mesylate Neoadjuvant Therapy to Preserve the Anus].

A woman in her 40's who initially presented with anal pain was diagnosed with rectal GIST. A 9 cm tumor extended to near the anus, and curative abdominoperineal tumor resection was required. The patient initially received neoadjuvant therapy with imatinib mesylate. Neoadjuvant chemotherapy for 6 months reduced the tumor to approximately 47% of its original size and permitted anus-preserving surgery. The present case suggests that neoadjuvant therapy with imatinib mesylate is useful for large rectal GISTs, from the standpoint of anal function preservation.