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