 4. Stage I, II, and III patients are eligible if the primary tumor is 6 centimeter or larger. All stage IV 4 metastatic or recurrent GIST patients who are imatinib-naïve are eligible. For stage IV patients who had initial good response to imatinib and stopped imatinib for 10 months or longer. GIST patients who received imatinib as adjuvant treatment in the past, later developed a recurrence are eligible only if the DFS is 6 months after completion of adjuvant imatinib. 