Therapeutic Trial for Patients With Ewing Sarcoma Family of Tumor and Desmoplastic Small Round Cell Tumors

Inclusion Criteria: * Group A participants must be \<14 years of age at time of diagnosis of histologically proven non-pelvic localized Ewing sarcoma family of tumor (ESFT) involving the bone or soft tissue. * Group B participants must have newly diagnosed of histologically proven ESFT involving the bone or soft tissue and at least one of the following: metastatic disease (must be biopsy proven), or pelvic primary, or ≥14 years of age at the time of diagnosis. * OR Group B participants must be newly diagnosed with intra-abdominal, unresectable or metastatic desmoplastic small round cell tumor. Metastatic site must be biopsy proven. * Age must be ≤25 years. * Adequate bone marrow function defined as a peripheral absolute neutrophil count (ANC) ≥750/m\^3 and platelet count ≥75,000/m\^3 (no transfusion within 7 days of study enrollment). Patients with Ewing sarcoma metastatic to the bone marrow are not required to meet bone marrow criteria for study eligibility and are not evaluable for hematologic toxicity. * Must have adequate renal function based on age. * Must not have had prior chemotherapy or radiation therapy. Emergent radiotherapy to preserve vital organ function is permitted. Participants who receive emergent radiation will not be eligible for window therapy. * Must have adequate hepatic function defined as total bilirubin ≤3.0 mg/dL. * Must have adequate cardiac function defined as shortening fraction ≥28%. * Females of childbearing potential and males able to father …