Treatment : Patients will receive Glivec® 400 mg /day for an exposure period of 60 months. At the end of a 5 years period, patients with non progressive disease will be proposed for randomization between 1) interruption of Glivec® until progression w/ RECIST criteria and then re-start vs 2) maintenance of Glivec®. Patient who refuse randomization will be proposed either solution and followed according to the same schedule. During treatment with Glivec® 400mg/day, Glivec® may be increased to 600 mg/day or 800 mg/day if the patient is progressing. In case of re-progression, the patient will be excluded of this study.