Previously untreated patients referred to St. Jude Children's Research Hospital (SJCRH) between the ages of 0 and 21 years with a diagnosis of osteosarcoma, ESFT, rhabdomyosarcoma and intermediate and high-risk non-rhabdomyosarcoma soft tissue sarcomas whose planned treatment includes administration of a cumulative anthracycline dose ≥ 375 mg/m2.