Antineoplastic Combined Chemotherapy Protocols/therapeutic use; Hematopoietic Stem Cell Transplantation; Neoplasms/therapy; Adolescent; Adult; Amifostine/administration & dosage; Amifostine/adverse effects; Antineoplastic Combined Chemotherapy Protocols/adverse effects; Bone Marrow Transplantation; Bone Neoplasms/diagnosis; Bone Neoplasms/therapy; Carboplatin/administration & dosage; Central Nervous System Neoplasms/diagnosis; Central Nervous System Neoplasms/therapy; Child; Child, Preschool; Combined Modality Therapy; Cyclophosphamide/administration & dosage; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug-Related Side Effects and Adverse Reactions; Etoposide/administration & dosage; Feasibility Studies; Hodgkin Disease/diagnosis; Hodgkin Disease/therapy; Humans; Hypocalcemia/chemically induced; Hypocalcemia/pathology; Kidney Neoplasms/diagnosis; Kidney Neoplasms/therapy; Melphalan/administration & dosage; Neoplasms/diagnosis; Neuroblastoma/diagnosis; Neuroblastoma/therapy; Pilot Projects; Recurrence; Risk Factors; Sarcoma/diagnosis; Sarcoma/therapy; Transplantation, Autologous; Transplantation, Homologous; Treatment Outcome; Wilms Tumor/diagnosis; Wilms Tumor/therapy