Evaluation of Patients With Bulky GIST Using Sunitinib

Inclusion Criteria: * Patients more than 19 years old with pathologically proven GIST which is bulky or marginally resectable * Patients must have at least one bidimensionally measurable disease site of 5 cm or greater not previously irradiated. Bone lesions do not qualify. * Patients must have an ECOG performance of greater than or equal to 2, with projected survival of at least three months. * Patients must have adequate laboratory parameters: Hematologic: Hb \>9.0; WBC \>3200 and platelets \>100,000/mm3; Hepatic: Bilirubin \<2.0 and AST within 4 times upper limit of normal; Renal: Creatinine of less than or equal to 1.6 or eGFR greater than or equal to 50 mL/min * Men and women who are of childbearing potential must practice strict birth control for the duration of the study. * Women of childbearing potential must be non-lactating and non-pregnant with a negative pregnancy test within two weeks of trial registration. * The patient, a witness, and attending physician will have signed an IRB-approved informed consent prior to Sunitinib administration. Exclusion Criteria: * Known brain metastases or significant pleural effusion or ascites. * Uncontrolled hypertension, diabetes, or other medical condition. * Major surgery within 21 days of registration. * Patients wtih organ grafts with the exception of prior high dose chemotherapy with autologous bone marrow (or stem cell) transplantation. * History of seizures, central nervous system disorders, dementia, or psychosis that might preclude adequate informed consent or protocol compliance. * Prior therapy for GIST. * A history of HIV or hepatitis virus infection. * Any recent medical condition which, in the opinion of the investigator, makes the patient unsuitable for study participation. * Patients with impaired kidney function.