Radiation Therapy or Combination Chemotherapy in Treating Patients With Clinically or Radiologically Progressive Low-Grade Gliomas

DISEASE CHARACTERISTICS: * Histologically confirmed low-grade glioma, of 1 of the following histologic subtypes: * Pilocytic astrocytoma I° and variants * Subependymal giant cell astrocytoma I° * Dysembryoplastic neuroepithelial tumor I° * Desmoplastic infantile ganglioglioma I° * Ganglioglioma I° and II° * Pleomorphic xanthoastrocytoma II° * Oligodendroglioma II° * Oligoastrocytoma II° * Astrocytoma II° * Fibrillary astrocytoma II° * Protoplasmatic astrocytoma II° * Gemistocytic astrocytoma II° * Children with chiasmatic-hypothalamic tumors may be eligible without histological diagnosis, if neuroradiologic findings meet unequivocal criteria for the presence of a low-grade glioma * Primary tumor localization: intracranial and/or spinal cord * No diffuse intrinsic tumors of the pons, even if histologically an astrocytoma I° or II° is diagnosed * Exception: pontine glioma II° in neurofibromatosis type 1 (NF1) disease allowed * Children presenting with disseminated low-grade glioma will be eligible for the study * All eligible patients without NF1 disease receiving chemotherapy as their first nonsurgical therapy are eligible for randomization * Children are eligible for the trial regardless of the presence of associated genetic disease: NF1 disease will be the prominent one, all children with NF1 disease are entered into the study arm III in case of an indication for nonsurgical therapy * Patients presenting with rare intracranial neoplasms of low-grade malignancy, but nonglial origin, may be followed according to the low-grade glioma strategy, but they are not subject of this therapy trial. * Data from these patients may be registered to learn about those therapeutic interventions which may prove useful to these patients and to develop separate strategies in the future * Patients with choroid plexus papilloma should be entered into the SIOP-CPT study (Prof. Dr. J. Wolff, M.D. Anderson Cancer Center, Houston, Texas) PATIENT CHARACTERISTICS: * No preexisting impairments of health status, making the conduct of the study impossible or ethically unwise * No evidence of pregnancy or lactation period * Pregnancy has to be prevented in fertile adolescent girls during chemotherapy by reliable contraception methods (e.g., hormonal contraception) PRIOR CONCURRENT THERAPY: * The tumor should not be pretreated with chemotherapy or radiotherapy * Children treated with chemotherapy or radiotherapy prior to entering the study will be evaluated separately * Previous treatment with steroids is not considered a chemotherapeutic treatment * Surgery of any type and extent allowed * Prior surgical resection of the tumor allowed * Participation in another clinical study concurrently with this study (e.g., endocrinologic study) allowed provided it is not interfering with the present treatment strategy * No other concurrent chemotherapy * Concurrent medication for associated or other conditions (e.g., hormone replacement, anticonvulsants) that does not containing cytostatic drugs allowed INCLUSION CRITERIA * Age: children and adolescents up to the completion of the 18th year of life. * Histology: low grade glioma according to ICD O Code Children with chiasmatic-hypothalamic tumors may be eligible without histological diagnosis, if neuroradiologic findings meet unequivocal criteria for the presence of a low grade glioma. * Primary tumor localization: intracranial and/or spinal cord. * Dissemination: Children presenting with disseminated low grade glioma will be eligible for the study. * Associated conditions: Children are eligible for the trial regardless of the presence of associated genetic disease: Neurofibromatosis NF I will be the prominent one, all children with NF I are entered into the study arm III in case of an indication for non-surgical therapy. Other conditions like Tuberous Sclerosis etc. should be registered and their impact on the course of disease and/or therapy be followed. * Primary tumor diagnosis: The tumor should not be pretreated with chemotherapy or radiotherapy. * Informed consent: The patient and/or his legal guardian ( parents ) have to have declared their written informed consent to the study. Randomization: All eligible patients without Neurofibromatosis NF I receiving chemotherapy as their fist non-surgical therapy are eligible for randomization. EXCLUSION CRITERIA * Primary tumor localization: diffuse intrinsic tumors of the pons, even if histologically an Astrocytoma I° or II° is diagnosed. Exception: pontine glioma II° in NF I patients may be entered into the study. * Special diagnosis: Patients presenting with rare intracranial neoplasms of low grade malignancy, but non-glial origin may be followed according to the low grade glioma strategy but they are not subject of this therapy trial. Their data may be registered however, to learn about those therapeutic interventions which may prove useful to these patients and to develop separate strategies in the future. Choroid plexus papilloma should be entered into the SIOP-CPT study. * Pretreatment: Children treated with chemo- or radiotherapy prior to entering the study will be evaluated separately. (Previous treatment with steroids is not considered a chemotherapeutic treatment.) * Preexisting impairments of health status, making the conduct of the study impossible or ethically unwise. * Evidence of pregnancy or lactation period. Participation in another clinical study: In case the patient participates in another clinical study simultaneously to being enrolled in the study SIOP-LGG 2004, which is not interfering with the present treatment strategy ( e.g. endocrinologic study ), this should be known to the national study chairmen. Medication: Concomitant medication for associated or other conditions ( e.g. hormone replacement, anticonvulsants ), not containing cytostatic drugs, should be recorded, but is no exclusion criteria.