Imatinib Mesylate in Treating Patients With Locally Advanced Gastrointestinal Stromal Tumor

DISEASE CHARACTERISTICS:

* Histologically confirmed gastrointestinal stromal tumor

  * Locally advanced disease
  * Potentially resectable disease\*

    * No tumor that can be completely resected (R0) with sufficient margins NOTE: \*Multivisceral resection may be necessary
* Tumor must stain positive for c-Kit (CD117) or platelet-derived growth factor receptor-alpha (PDGFRA) by immunohistochemistry
* At least 1 site of measurable disease
* No known brain metastases

PATIENT CHARACTERISTICS:

Age

* 18 and over

Performance status

* ECOG 0-3

Life expectancy

* Not specified

Hematopoietic

* Platelet count \> 100,000/mm\^3
* Absolute neutrophil count \> 1,500/mm\^3

Hepatic

* AST and ALT \< 2.5 times upper limits of normal (ULN) (5 times ULN if hepatic metastases are present)
* Bilirubin \< 1.5 times ULN
* No chronic active hepatitis
* No cirrhosis
* No other chronic liver disease

Renal

* Creatinine \< 1.5 times ULN
* No chronic renal disease

Cardiovascular

* No New York Heart Association class III-IV cardiac disease
* No congestive heart failure
* No myocardial infarction within the past 6 months

Immunology

* No active uncontrolled infection
* No known HIV positivity

Other

* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective barrier contraception during and for 3 months after completion of study treatment
* Must be medically fit to undergo surgery
* No other primary malignancy within the past 5 years except basal cell skin cancer, carcinoma in situ of the cervix, or a primary malignancy that is not currently clinically significant and does not require active intervention
* No gastrointestinal obstruction or major bleeding episode requiring immediate surgical intervention
* No uncontrolled diabetes
* No other severe or uncontrolled medical disease
* No significant history of noncompliance to medical regimens

PRIOR CONCURRENT THERAPY:

Biologic therapy

* No concurrent anticancer biologic agents

Chemotherapy

* More than 4 weeks since prior chemotherapy (6 weeks for nitrosourea or mitomycin) unless disease is rapidly progressing
* No concurrent anticancer chemotherapy

Endocrine therapy

* No concurrent systemic corticosteroid therapy unless approved by the study sponsor

Radiotherapy

* More than 4 weeks since prior radiotherapy
* No prior radiotherapy to ≥ 25% of bone marrow

Surgery

* More than 2 weeks since prior major surgery except tumor biopsy

Other

* More than 4 weeks since prior investigational drugs unless disease is rapidly progressing
* No other concurrent anticancer therapy
* No other concurrent investigational agents
* No concurrent warfarin for therapeutic anticoagulation

  * Concurrent low molecular weight heparin (e.g., enoxaparin sodium) or heparin for therapeutic anticoagulation allowed
  * Concurrent mini-dose warfarin (e.g.,1 mg/day) for prophylaxis of central venous catheter thrombosis allowed