6. Performance Level: Karnofsky ≥ 60% for patients > 16 years of age and Lansky ≥ 60 for patients ≤16 years of age. Note: Neurologic deficits in patients with tumors of the CNS (central nervous system) must have been relatively stable for a minimum of 1 month prior to study enrollment. Patients who are unable to walk because of paralysis, but who are up in a wheelchair, will be considered ambulatory for the purpose of assessing the performance score.