Preoperative and Postoperative Imatinib Mesylate Study in Patients With c-Kit Positive GIST

Primary objectives 1. To determine whether induction of apoptosis or inhibition of angiogenesis are involved in the antitumor activity of (Gleevec, Formerly STI-571) in patients with gastrointestinal stromal tumors (GIST) as assessed by Positron Emission Tomography (PET) scanning. 2. To determine whether dynamic computed tomography (CT), PET scan, molecular and histopathologic responses in GIST tumors from patients treated with Gleevec predict Disease-Free Survival (DFS) time. Secondary objectives 1. To determine the disease free survival of patients with resectable or partially resectable gastrointestinal stromal tumors treated with Gleevec preoperatively and continued for 2 years after resection of disease. 2. To assess the safety and tolerability of Gleevec given to patients with GI stromal tumors 3, 5, or 7 days preoperatively and continued postoperatively.