PBSCT GROUP: Patients receive etoposide IV continuously and HiDAC IV over 2 hours every 12 hours on days 1-4. Patients also receive filgrastim (G-CSF) subcutaneously (SC) daily beginning on day 14 and continuing until peripheral blood stem cell (PBSC) collection is completed. Patients who are not able to undergo PBSCT after HiDAC/etoposide continue treatment in the non-PBSCT group. At least 4 weeks after HiDAC/etoposide recovery, patients receive oral busulfan every 6 hours on days -7 to -4 and etoposide IV over 4 hours on day -3 prior to PBSCT. Patients receive autologous PBSC infusion on day 0. Patients also receive G-CSF SC beginning on day 0 and continuing until hematopoietic recovery.