PEG-Interferon Alfa-2b in Treating Young Patients With Plexiform Neurofibroma

DISEASE CHARACTERISTICS: Diagnosis of plexiform neurofibroma which is progressive, symptomatic, or life threatening and for which there is no other standard medical management or surgical option Histologic confirmation of tumor is not required in the presence of consistent clinical and radiographic findings provided the following are true: No clinical observation or scan suggestive of malignant transformation Meets ≥ 1 of the following diagnostic criteria for neurofibroma type 1 (NF1): Six or more cafe-au-lait spots (> 0.5 cm in prepubertal patients or > 1.5 cm in post pubertal patients) Freckling in axilla or groin Optic glioma Two or more Lisch nodules A distinctive bony lesion (e.g., dysplasia of the sphenoid bone, dysplasia, or thinning of long bone cortex) A first degree relative with NF1 No history of malignant peripheral nerve sheath tumor No active visual pathway glioma No active brain tumor or brain metastases PATIENT CHARACTERISTICS: Performance status ECOG 0-2 Life expectancy At least 12 months Hematopoietic Absolute neutrophil count > 1,500/mm^3 Hemoglobin > 10 g/dL Platelet count > 100,000/mm^3 Hepatic Bilirubin < 1.5 mg/dL SGPT ≤ 2 times upper limit of normal No significant hepatic dysfunction Renal Creatinine based on age as follows: ≤ 0.8 mg/dL (for patients age 5 years and under) ≤ 1.0 mg/dL (for patients age 6 to 10 years) ≤ 1.2 mg/dL (for patients age 11 to 15 years) ≤ 1.5 mg/dL (for patients age 16 to 21 years) OR Creatinine clearance ≥ 70 mL/min Cardiovascular No significant cardiac dysfunction No severe cardiovascular disease No cardiac arrhythmia requiring chronic treatment No congestive heart failure No symptomatic ischemic heart disease Pulmonary No significant pulmonary dysfunction Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No serious infection No other significant unrelated systemic illness No significant organ dysfunction No other malignancy except surgically cured nonmelanoma skin cancer or carcinoma in situ of the cervix No history of severe psychiatric condition or psychiatric disorder requiring hospitalization No history of suicidal ideation or attempt No thyroid dysfunction unresponsive to therapy No uncontrolled diabetes mellitus No history of HIV positivity No alcohol or drug abuse PRIOR CONCURRENT THERAPY: Biologic therapy No concurrent immunotherapy No concurrent colony-stimulating factors (e.g., erythropoietin or filgrastim [G-CSF]) Chemotherapy No concurrent chemotherapy for this disease Endocrine therapy No concurrent chronic systemic corticosteroids No concurrent hormonal therapy for this disease Radiotherapy No concurrent radiotherapy for this disease Surgery Prior surgery allowed provided it has been at least 21 days since surgery and there is presence of residual tumor Other Recovered from prior therapy More than 30 days since prior investigational agents