Outcomes of adolescent males with extracranial malignant germ cell tumors compared with children and young adults: A report from the Malignant Germ Cell Tumors International Consortium (MaGIC) group

10022 Background: Adolescents with extracranial malignant germ cell tumors (GCTs) are often treated on the same regimens developed for children, but more closely resemble the clinical characteristics of young adult patients. We sought to determine whether event-free survival (EFS) for adolescents with GCTs was more like that of children or young adults. Methods: We assembled an individual patient database of ten GCT trials: seven conducted by pediatric cooperative groups and three by an adult group. We selected male patients aged 0-30 years old treated with platinum-based chemotherapy for non-seminomatous malignant GCTs of the testis, retroperitoneum, or mediastinum. We categorized age-group as children (0 to < 11 years), adolescents (11 to < 18 years), or young adults (18 to < 30 years old). We compared EFS among age groups, and adjusted for calculated IGCCCG risk-group using Cox proportional hazards analysis. Results: 593 patients met inclusion criteria, of whom 90 were children, 109 were adolescents, and 394 were young adults. The 5-year EFS for adolescents (72%; CI = 62-79%) was significantly lower than for children (90%; CI = 81-95%, p = 0.003) and for young adults (88%; CI = 84-91%, p < 0.001). Risk-group was significantly associated with EFS in the adolescent age-group (p = 0.002). In a Cox multivariable analysis, the difference between adolescents and children remained statistically significant (HR = 0.30, p = 0.001), but the difference between adolescents and young adults did not (HR 0.66, p = 0.114). Conclusions: EFS for adolescent patients with extracranial malignant GCTs was similar to young adults but significantly worse than children. This finding may have important implications for how adolescent patients are treated.