- Group B (prior radiation greater than 2,000 cGy): Patients with CR or PR after completion of chemotherapy receive oral busulfan every 6 hours on days -7 to -4, followed by cyclophosphamide IV over 1 hour on days -3 and -2. Patients with minimal response after completion of chemotherapy receive oral busulfan every 6 hours on days -9 to -6, followed by cyclophosphamide IV over 1 hour on days -5 and -4, followed by etoposide IV over 30 hours beginning on day -3.