Outcome of Children With Intermediate-Risk Extracranial Malignant Germ Cell Tumors by Response Status at the End of Induction Chemotherapy: A Report From the Children's Oncology Group.

Background: In many pediatric malignant germ cell tumor (MGCT) protocols, patients who do not achieve a complete response (CR; normal tumor markers, no radiological/histological residual) after three cisplatin-etoposide-bleomycin (PEb) cycles receive two to three "consolidation" cycles of the same regimen. Evidence for this practice is limited, and historical outcomes for non‑CR patients remain poor.

Methods: We retrospectively reviewed patients diagnosed with intermediate-risk MGCT, enrolled in AGCT0132, between 2003 and 2011. All patients received three cycles of PEb and underwent response assessment at the end of induction. Patients not in CR were prescribed three additional cycles of PEb as consolidation. We compared event-free survival (EFS) and overall survival (OS) for patients who did and did not receive consolidation.

Results: Among 210 patients enrolled, two patients were excluded from analyses: one without complete information, and one had rapid progressive disease (PD) and did not complete induction therapy. Out of 208 patients, 193 had a CR after three cycles of induction chemotherapy, and their post-induction 4-year EFS and OS were 93% and 99%. Fifteen patients were not in CR at the end of the first three cycles. Twelve received consolidated chemotherapy as mandated per protocol, and their 4-year EFS and OS were 61% and 65%, respectively. Three patients were deemed to have progressive disease at the end of induction and received second-line therapy.

Conclusion: Children with MGCTs who did not achieve CR after the first three cycles of chemotherapy had an inferior outcome compared to those with a CR, despite receiving additional cycles of PEb chemotherapy. We conclude that consolidation is of unclear benefit. We suggest that pediatric MGCT patients who fail to achieve a CR after standard induction chemotherapy may receive a salvage regimen with different agents rather than consolidation with more of the same chemotherapy.