Neoadjuvant and Adjuvant Imatinib Mesylate in Treating Patients With Primary or Recurrent Malignant Gastrointestinal Stromal Tumor

Phase II trial to study the effectiveness of neoadjuvant and adjuvant imatinib mesylate in treating patients who are undergoing surgery for primary or recurrent malignant gastrointestinal stromal tumor. Imatinib mesylate may stop the growth of tumor cells by blocking the enzymes necessary for their growth. Giving imatinib mesylate before and after surgery may shrink the tumor so it can be removed and may kill any tumor cells remaining after surgery.