OUTLINE: Mobilization/harvest: Patients receive cytarabine IV over 2 hours every 12 hours and etoposide IV continuously on days 1-4. Filgrastim (G-CSF) is administered subcutaneously (SC) beginning on day 14 and continuing until peripheral blood stem cells (PBSC) are harvested. When blood counts recover, PBSC are harvested and selected for CD34+ cells. Conditioning: Beginning at least 4 weeks after hospital discharge for mobilization and harvest and when blood counts recover, patients receive oral busulfan every 6 hours on days -7 to -4 and etoposide IV over 4 hours on day -3. PBSC are reinfused on day 0. G-CSF is administered SC beginning on day 0 and continuing until blood counts recover. Patients with documented CNS disease at first relapse receive methotrexate intrathecally at intervals of 1 week or greater before and/or after PBSC transplantation for a total of 6 doses. Patients are followed every 3 months for 2 years and then every 6 months for 3 years.