Topotecan Active Not Recruiting Phase 3 Trials for Extraosseous Ewing Sarcoma / Untreated Childhood Supratentorial Primitive Neuroectodermal Tumor / Ewing Sarcoma of Bone / Peripheral Primitive Neuroectodermal Tumor of Soft Tissues / Extraosseous Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor / Peripheral Primitive Neuroectodermal Tumor of Bone / Non-Metastatic Extraskeletal Ewing Sarcoma / Peripheral Primitive Neuroectodermal Tumor of the Kidney / Localized Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor / Childhood Supratentorial Primitive Neuroectodermal Tumor / Adult Supratentorial Primitive Neuroectodermal Tumor (PNET) Treatment