Children with unresectable/incompletely-resectable tumors, or those with relapsed disease and those observed following incomplete initial resection or neuroradiologic diagnosis and clinical and/or neuro-radiologic progression receive non-surgical therapy. This non-surgical therapy is either chemotherapy (for children younger than 8 years and those with neurofibrosis-type 1 [NF1]) or radiotherapy (for children older than 8 years).