Revised Risk Classification for Pediatric Extracranial Germ Cell Tumors Based on 25 Years of Clinical Trial Data From the United Kingdom and United States

PURPOSE: To risk stratify malignant extracranial pediatric germ cell tumors (GCTs). PATIENTS AND METHODS: Data from seven GCT trials conducted by the Children's Oncology Group (United States) or the Children's Cancer and Leukemia Group (United Kingdom) between 1985 and 2009 were merged to create a data set of patients with stage II to IV disease treated with platinum-based therapy. A parametric cure model was used to evaluate the prognostic importance of age, tumor site, stage, histology, tumor markers, and treatment regimen and estimate the percentage of patients who achieved long-term disease-free (LTDF) survival in each subgroup of the final model. Validation of the model was conducted using the bootstrap method. RESULTS: In multivariable analysis of 519 patients with GCTs, stage IV disease (P = .001), age ≥ 11 years (P < .001), and tumor site (P < .001) were significant predictors of worse LTDF survival. Elevated alpha-fetoprotein (AFP) ≥ 10,000 ng/mL was associated with worse outcome, whereas pure yolk sac tumor (YST) was associated with better outcome, although neither met criteria for statistical significance. The analysis identified a group of patients age > 11 years with either stage III to IV extragonadal tumors or stage IV ovarian tumors with predicted LTDF survival < 70%. A bootstrap procedure showed retention of age, tumor site, and stage in > 94%, AFP in 12%, and YST in 27% of the replications. CONCLUSION: Clinical trial data from two large national pediatric clinical trial organizations have produced a new evidence-based risk stratification of malignant pediatric GCTs that identifies a poor-risk group warranting intensified therapy.