Gastrointestinal stromal tumors (GISTs) are rare in the rectum. Radical surgery, such as an abdominoperineal resection, is necessary for large rectal GISTs, which can result in the loss of function of involved organs. Imatinib mesylate can be used as perioperative therapy and may reduce tumor size, and it is now approved for use in the adjuvant therapy of locally resected anorectal GISTs. The present study describes two cases of large rectal GISTs, for which abdominoperineal resections were initially planned. The two patients received pre-operative imatinib mesylate treatment, and the therapeutic response was assessed by magnetic resonance imaging. Finally, transsacral local resection was successfully performed for these two GISTs. A macroscopically complete resection was achieved, and microscopically, the resection margin was negative. One patient experienced the complication of rectal leakage, which was successfully managed by drainage. No recurrence occurred in the two patients after more than two years. Pre-operative imatinib mesylate therapy with subsequent transsacral local resection for selected rectal GISTs is a feasible treatment modality and can prevent extended surgery.
Keywords: imatinib mesylate; neoadjuvant treatment; rectal gastrointestinal stromal tumor; transsacral resection.