Purpose: To investigate prognostic factors for pediatric extragonadal malignant germ cell tumors (PEMGCT).
Materials and methods: Between 1990 and 1996, patients with stage I through IV PEMGCT were eligible for a trial of cisplatin dose intensity. We retrospectively investigated prognostic factors for PEMGCT, including age, stage, primary site, treatment, and elevated alfa fetoprotein by univariate and multivariate analysis.
Results: The 165 patients had a median age of 1.9 years (range, 3 days to 18.5 years); 109 were female; and 99 had alfa fetoprotein > or = 10,000. There were 30 stage I/II, 61 stage III, and 74 stage IV tumors; primary sites included 88 sacrococcygeal, 39 thoracic, and 38 others. The 5-year overall survival (OS) and event-free survival (EFS) rates with standard deviations were 83.4% +/- 3.7% and 79.0% +/- 4.1%, respectively. Univariate analysis identified age > or = 12 years as a highly significant prognostic factor for EFS (5-year EFS, 48.9% +/- 15.6% v 84.1% +/- 3.9%; P < .0001) and for OS (5-year OS, 53.7% +/- 14.9% v 88.5% +/- 3.4%; P < .0001), whereas treatment was of borderline significance (P = .0777). Multivariate Cox proportional hazards regression identified only age > or = 12 years as a significant prognostic factor for EFS (P = .0002). In multivariate Cox regression for OS, the combination of age and primary site was highly significant (P < .0001). Patients > or = 12 years of age with thoracic tumors had six times the risk of death compared with patients younger than 12 years with other primaries.
Conclusion: Age is the most predictive factor of EFS in PEMGCT. There is a significant interaction between age and primary site, suggesting that patients > or = 12 years of age with thoracic tumors are a biologically distinct group.