In this study, the investigators aim to investigate the efficacy and safety of 5 years of adjuvant imatinib treatment in patients with tumor rupture defined by Nishida classification or those with a tumor size 10cm or larger and a mitotic index of 10/50HPFs or higher.
Age 20 years or older, at the time of acquisition of informed consent
Histologically confirmed GIST with CD117(+), DOG-1(+), or mutation in KIT or PDGFRα gene
(1) Completely resected localized GIST (R0 resection) within 12 weeks prior to the start of the adjuvant imatinib.
Tumor rupture according to Nishida classification or
Women of child-bearing potential who are pregnant or breast feeding
Women or men who are not willing to use effective contraception entering the study period or until at least 3 months after the last study drug administration.
If any of the following applies within ≤ 6 months prior to starting study enrollment : Myocardial Infarction, severe instable angina, coronary/peripheral bypass, NYHA class III or IV congestive heart failure, stroke or transient ischemic attack, treatment required severe arrhythmia.
Uncontrolled infection