RADIOTHERAPY: Patients with stage 2 or 3 disease (orbital and/or regional involvement) undergo radiotherapy to sites that were initially involved beginning within 42 days after the start of course 4 of induction chemotherapy. Patients with stage 4a or 4b disease undergo radiotherapy to sites initially involved based on response beginning approximately 42 days after autologous stem cell infusion. Patients with stage 4a disease who achieve a complete response to induction chemotherapy or with less than 5 mm of residual tumor at the time of planned irradiation, or patients with stage 4b disease who achieve a complete response to induction chemotherapy do not undergo radiotherapy.