Neoadjuvant imatinib and organ preservation in locally advanced gastrointestinal stromal tumors (GIST)

10550 Background: We assessed the outcome of patients with locally advanced gastrointestinal stromal tumors (GIST) undergoing preoperative therapy with imatinib. Methods: 36 patients with biopsy proven GIST (23 f, 13 m, median age 58 (27–85) yrs, 31 primary tumors, 5 local recurrences) of the esophagus/EGJ (n=5), stomach (n=17), duodenum (n=2), small bowel (n=3), or rectum (n=9) were treated with imatinib 400mg/d for 6 mos. preop. Six pts had been found unresectable at exploratory lap. and no pt. had signs of metastases on CT/MRI and/or FDG-PET. Average tumor size was 10.5 cm (4–28 cm). According to Consensus two tumors were low risk, 11 intermediate, and 23 were high risk for aggressive behaviour. 33 pts were symptomatic. Extent of surgery, local outcome, morbidity and response to therapy were analyzed; median follow-up is 22 mos. Results: Median treatment duration was 11 mos. (range 2–31 mos). Successful dose adjustment for exon 9 mutation to 800 mg imatinib/d was used in two pts. 33 pts. completed the ...