Imatinib Mesylate With or Without Surgery in Treating Patients With Metastatic Gastrointestinal Stromal Tumor That is Responding to Imatinib Mesylate

RATIONALE: Surgery may remove residual disease in patients with gastrointestinal stromal tumor that is responding to imatinib mesylate. It is not yet known whether surgery is more effective than continued imatinib mesylate in treating patients with metastatic gastrointestinal stromal tumor. PURPOSE: This randomized phase III trial is studying giving imatinib mesylate therapy together with surgery to see how well it works compared with imatinib mesylate alone in treating patients with metastatic gastrointestinal stromal tumor that is responding to imatinib mesylate.