OUTLINE: This is a dose escalation study of topotecan. Patients are primed with cyclophosphamide IV over 2 hours for 2 days. Peripheral blood stem cells (PBSC) are collected. Approximately 4 weeks after PBSC collection, patients receive melphalan IV over 30 minutes and topotecan IV over 30 minutes on days -7 to -5. Etoposide phosphate IV is administered over 4 hours on days -4 and -3. PBSC are reinfused on day 0. Cohorts of 4-12 patients receive escalating doses of topotecan until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 6 of 12 patients experience dose limiting toxicities. Patients are followed 2-3 times a week for approximately 1 month, then at 3, 6, and 12 months.