BACKGROUND: From 1993 to 1995, the Pediatric Oncology Group (POG) enrolled patients with high-risk neuroblastoma on three sequential, conjoined studies: a phase II induction window (9340), followed by intensive multiagent induction chemotherapy (9341), and subsequent myeloablative therapy with autologous stem cell rescue (9342). We report here the outcomes of patients treated on these studies. PATIENTS AND METHODS: Patients were between 1 and 21 years old with high-risk neuroblastoma. Phase II window therapy consisted of two courses of either paclitaxel, topotecan, or cyclophosphamide with topotecan. Induction therapy consisted of at least five cycles of intensive chemotherapy, followed by myeloablative therapy with purged autologous stem cell reinfusion. Patient responses, treatment toxicities, and overall and event-free survival rates were calculated. RESULTS: Eighty-four percent of patients responded to induction chemotherapy, with 39% achieving complete response. Toxicities were primarily hematologic. The 7-year EFS and OS rates for all eligible patients on POG 9341 were 23 +/- 4% and 28 +/- 4%, respectively. The 7-year EFS and OS rates for patients treated on POG 9342 were 27 +/- 6% and 29 +/- 6%, respectively. CONCLUSIONS: These studies were the first attempt by POG to use autologous stem cell transplantation for neuroblastoma treatment in a cooperative group setting. Toxicities and outcomes were comparable to contemporary cooperative group studies. The phase II induction window had no detectable effect on outcomes. New strategies are needed to improve survival for this devastating disease.