One vs Three Years of Adjuvant Imatinib for Operable Gastrointestinal Stromal Tumor

To investigate the role of imatinib administration duration as adjuvant treatment of patients who have a high estimated risk for GIST recurrence after surgery. DESIGN, SETTING, AND PATIENTS: Patients with KIT-positive GIST removed at surgery were entered between February 2004 and September 2008 to this randomized, open-label phase 3 study conducted in 24 hospitals in Finland, Germany, Norway, and Sweden. The risk of GIST recurrence was estimated using the modified National Institutes of Health Consensus Criteria. INTERVENTION: Imatinib, 400 mg per day, orally for either 12 months or 36 months, started within 12 weeks of surgery. MAIN OUTCOME MEASURES: The primary end point was RFS; the secondary end points included overall survival and treatment safety.

Two hundred patients were allocated to each group. The median follow-up time after randomization was 54 months in December 2010. Diagnosis of GIST was confirmed in 382 of 397 patients (96%) in the intention-to-treat population at a central pathology review. KIT or PDGFRA mutation was detected in 333 of 366 tumors (91%) available for testing. Patients assigned for 36 months of imatinib had longer RFS compared with those assigned for 12 months (hazard ratio [HR], 0.46; 95% CI, 0.32-0.65; P