Imatinib Mesylate in Treating Patients With Recurrent or Refractory Fibromatosis

DISEASE CHARACTERISTICS: Histologically confirmed aggressive fibromatosis (desmoid tumor) Relapse or disease progression despite surgery, chemotherapy, radiotherapy, or any other treatment Tumors must meet the following criteria: Ineligible for complete surgical resection by carcinological exeresis OR surgery would cause severe mutilation Cannot be treated with curative radiotherapy Measurable disease by RECIST criteria No prior malignancy PATIENT CHARACTERISTICS: Not pregnant or nursing Fertile patients must use effective contraception during and for 6 months after completion of study treatment Absolute neutrophil count > 1,000/mm^3 Platelet count > 100,000/mm^3 Bilirubin < 1.5 times upper limit of normal (ULN) SGOT and SGPT < 2.5 times ULN Creatinine ≤ 2.5 times normal No severe liver failure No chronic somatic or psychiatric illness that would preclude study compliance No known hypersensitivity to imatinib mesylate or one of its components No geographical, social, or psychological reason that would inhibit follow-up PRIOR CONCURRENT THERAPY: See Disease Characteristics No concurrent immunomodulators* No concurrent hormonal treatments* if used for fibromatosis No concurrent cytotoxic drugs* No concurrent nonsteroidal anti-inflammatory drug* if used for fibromatosis Allowed if used as an analgesic 3 months prior to disease progression No concurrent participation in another therapeutic investigational trial NOTE: *If disease progression has occurred during this treatment, then the treatment must have ended ≥ 1 month prior to study entry