PROJECTED ACCRUAL: A total of 595 case patients (12 with soft tissue sarcoma, 34 with osteosarcoma, 19 with brain tumors, 32 with Hodgkin's disease, 60 with non-Hodgkin's lymphoma, 278 with acute lymphoblastic leukemia, 65 with acute non-lymphoblastic leukemia, 56 with neuroblastoma, 14 with hepatoblastoma, and 25 with germ cell tumors) will be accrued for this study within 7 years. Corresponding control patients will be accrued for this study.