- Group 2 (high-risk): Patients receive topotecan IV over 4 hours on days 1-5 and G-CSF SC or IV beginning 24 hours after completion of the first course of topotecan and continuing until PBSC are harvested. Treatment repeats every 3 weeks for 2 courses. If an adequate number of PBSC are not harvested, the patient undergoes a second harvest of PBSC after the second course of topotecan. Patients then receive CSI, high-dose chemotherapy, amifostine, and PBSC support as in group 1. (Topotecan window closed to accrual 9/10/2001) Patients undergo neuropsychological testing prior to radiotherapy and chemotherapy and then at 1, 2, and 5 years.