Neoadjuvant imatinib in gastrointestinal stromal tumor of the rectum: report of a case.

Gastrointestinal stromal tumors are rare tumors of the gastrointestinal tract. Gastrointestinal stromal tumors involving the rectum are uncommon. We describe a case of a 43-year-old female with a gastrointestinal stromal tumor of the rectum who declined abdominoperineal resection. Neoadjuvant treatment with imatinib decreased her tumor size, permitting sphincter-sparing transanal excision. She had no evidence of disease for 24 months postoperatively until she recurred with lung metastases. Microdissection genotyping of the recurrent lesion revealed a deletion in exon 11. Further mutational analysis showed that her metastatic lesion was concordant with her primary rectal lesion, suggesting that systemic micrometastasis was previously present at initial diagnosis. Deletion in exon 11 predicts for response with imatinib treatment and is associated with a longer event-free and overall survival. Current studies are underway that may help us optimize the treatment for patients with gastrointestinal stromal tumors.