| Active, not recruiting | N/A | 956 | Canada, US, RoW | Biomarker Analysis, Blood Product Collection, Collection, Blood Products | SWOG Cancer Research Network, National Cancer Institute (NCI) | Germ Cell Tumor, Metachronous Malignant Neoplasm, Seminoma, Stage I Testicular Cancer AJCC v8, Stage IA Testicular Cancer AJCC v8, Stage IB Testicular Cancer AJCC v8, Stage IS Testicular Cancer AJCC v8 | 06/26 | 10/26 | | |