Brief Summary: A Non-Therapeutic Study that aims to establish a cohort of GCT survivors to understand short term and long-term adverse effects of treatment and to conduct molecular analyses to improve risk stratification.

Detailed Description: PRIMARY OBJECTIVES: I. Establish a survivorship cohort for pediatric and adolescent GCT comprised of participants from AEPI10N1 and APEC14B1 to assess short term and long-term adverse events associated with GCT treatment. II. Compare somatic variation by tumor histology to identify molecular signatures that improve prognostic risk stratification. III. Identify methylation patterns that predict poor clinical outcomes, including disease relapse and death. OUTLINE: Medical records from pediatric and adolescent Germ Cell Tumor (GCT) participants from AEPI10N1 and APEC14B1 will be used to obtain treatment information and validate self-reported outcomes. Paired normal and tumor samples will be used to evaluate single nucleotide variants, indels, copy number variations, and DNA methylation patterns. Ototoxicity will be determined by central review of audiogram files obtained from the treating institutions and self-reported based on questionnaire data.