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

Inclusion Criteria: * Histologically confirmed malignant gastrointestinal stromal tumor * Potentially resectable primary disease * Potentially resectable recurrent disease * Local or intra-abdominal/pelvic metastatic disease * Documented c-kit (CD117) expression by immunohistochemical analysis of either initial core specimen or, if recurrent disease, from original tumor block * Primary disease must be visceral, intra-abdominal, or pelvic in origin * At least 1 unidimensionally measurable lesion * At least 5 cm for primary disease * At least 2 cm for recurrent disease * At least 1 viable core biopsy tumor specimen obtained within 8 weeks before registration * Performance status - Zubrod 0-2 * WBC at least 3,000/mm\^3 * Absolute neutrophil count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 * Bilirubin no greater than 1.5 times upper limit of normal (ULN) * ALT/AST no greater than 2.5 times ULN * No uncontrolled chronic liver disease * Creatinine no greater than 1.5 times ULN * No uncontrolled chronic renal disease * No New York Heart Association class III or IV cardiac disease * Must be able to lie still in the PET scanner for approximately 1-2 hours * No uncontrollable hyperglycemia * No medical or psychological condition that would preclude study participation * No severe or uncontrolled medical disease * No active uncontrolled infection * No known or suspected hypersensitivity to any component of the study drug * Any prior malignancy is allowe…