 After stem cells are collected, patients will receive high-dose chemotherapy. Cyclophosphamide is given over 2 hours on Days 1 - 3. Melphalan is given on Days 4 and 5. Topotecan is given over 30 minutes on Days 1 - 5, right after cyclophosphamide or melphalan. On Day 6, no drugs are given. On Day 7, some or all of the stem cells will be reinfused. G-CSF will be given once a day until blood counts return to normal. 