High-dose chemotherapy with autologous stem cell transplantation for patients with extracranial germ cell tumors - experience of two Brazilian pediatric centers.

Malignant extracranial germ cell tumors (GCTs) are rare in pediatric patients and are usually extremely sensitive to chemotherapy. Relapsed or refractory tumors, although rare, established the need for second-line therapies, including high-dose chemotherapy with autologous stem cell transplantation (HDCT/ASCT). However, there are few data on its use in children with GCTs. We present a retrospective analysis of all patients diagnosed with extracranial GCTs who received HDCT/ASCT at two Brazilian pediatric cancer centers from May 1999 to December 2019. We identified a total of 34 patients with a median age at diagnosis of 2.8 years (range, 0 to 18.8), who received HDCT/ASCT. Most patients (73%) received carboplatin, etoposide and melphalan (CEM) as a HDCT regimen. Fourteen patients received a second-line conventional dose chemotherapy (CDCT), 14 received a third-line CDCT and five received even a fourth-line CDCT prior to HDCT/ASCT. After a median follow-up of 22.7 months (range, 0.3 to 198.1), 16 patients had died after tumor relapse/progression and 2 patients died from HDCT/ASCT toxicity. We observed a 5-year OS of 47.1% and 5-year EFS of 44.1%. The 5-year OS for patients referred for HDCT/ASCT with progressive disease was 10% compared to 62.5% for those who achieved disease control before HDCT/ASCT (p = 0.001). In our experience, heavily pretreated children and adolescents with extracranial GCTs achieved considerable survival rates with HDCT/ASCT since, at least, partial control of their disease was possible before starting HDCT/ASCT. The role of HDCT/ASCT in pediatric patients with GCTs should be investigated in prospective trials.