Interferon Alfa in Treating Patients With Recurrent Unresectable Meningiomas and Malignant Meningiomas

DISEASE CHARACTERISTICS: Histologically proven tumors: Unresectable meningioma Atypical meningioma Malignant meningioma Angioblastic meningioma Hemangiopericytoma Recurrent or progressive, unresectable tumor after failing radiation therapy or refused radiation therapy following 2 surgeries PATIENT CHARACTERISTICS: Age: 16 and over Performance status: Karnofsky at least 60% Life expectancy: At least 3 months Hematopoietic: AGC at least 1,500/mm^3 Platelet count at least 100,000/mm^3 Hepatic: SGPT less than 2.0 times normal Alkaline phosphatase less than 2.0 times normal Bilirubin less than 1.5 mg/dL Renal: BUN less than 1.5 times normal OR Creatinine less than 1.5 times normal Other: No active infection No diseases that obscure toxicity or dangerously alter drug metabolism No serious intercurrent medical illness Not pregnant Fertile patients must use adequate contraception PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent biologic therapy Chemotherapy: Prior chemotherapy allowed and recovered from all myelotoxicity secondary to the therapy Endocrine therapy: Prior hormonal therapy allowed No concurrent hormonal therapy Radiotherapy: Prior radiotherapy allowed Surgery: Not specified