Application of the adult International Germ Cell Classification System to pediatric malignant non‐seminomatous germ cell tumors: A report from the Children's Oncology Group

Abstract

The purpose of this analysis is to explore whether the International Germ Cell Classification Consensus (IGCCC) tumor marker criteria, developed for adult males with metastatic malignant germ cell tumors (MGCT), are prognostic among pediatric patients and whether tumor marker data may be relevant in pediatric risk stratification. The IGCCC was applied to 436 pediatric germ cell patients treated on Pediatric Intergroup Studies from 1990 to 1996. Multivariable Cox proportional hazards model identified prognostic variables; survival rates among IGCCC risk groups were compared using the log-rank test. Concordance and relative performance of IGCCC versus COG risk stratification was evaluated. Applying the IGCCC, 21% of pediatric patients were good risk (GR), 35% intermediate risk (IR), and 44% poor risk (PR). Only modest concordance between IGCCC and COG stratification systems was noted (49%). Nonetheless, the IGCCC identified a group of PR patients who had significantly worse event-free survival (EFS) versus GR/IR patients (6-year EFS 80% vs. 91%), which was similar to the difference observed using the COG system (6-year EFS 77% vs. 90%). The IGCCC performed well within subgroups for which the IGCCC is not intended (prepubertal, female, and non-metastatic patients). Applying the IGCCC system to pediatric patients produces a different stratification than does the application of the COG system, although both are prognostic. Development of a de novo pediatric prognostic classification is warranted.