Study of Intensive Chemotherapy, Surgery and Radiotherapy to Treat Ewing's Sarcoma in Children and Young Adults

Inclusion Criteria: * Patients with Ewing's Sarcoma in which the molecular analysis has been performed in one of the 2 reference laboratories of the study and the EWS gene rearrangement has been confirmed by RT-PCR in the Hospital Sant Joan de Déu de Barcelona, or by fluorescence in situ hybridization (FISH) in the Cancer Research Center of Salamanca. * High-risk patients will be those patients with metastases, patients with primary tumor in pelvis or axial bones and patients with (micro) metastases in bone marrow detected by the molecular study. The remaining patients will be considered as standard risk. Lung nodules identified by CT-scan with diameter \> 5 mm will be considered metastatic. Nodules ≤ 5 mm will be biopsied. * Age ≤ 40 years. * Adequate renal and hepatic function , defined as calculated creatinine clearance \> 60 ml/min, creatinine, total bilirubin, AST and/or ALT \< 1,5 times the upper limit of normal (ULN). * Normal cardiac function defined by echocardiography, or ejection fraction ≥ 55%. * ECOG performance status 0 - 1 (Appendix VIII). * Informed consent form signed by parents, guardians or the patient (if over 18 years), prior to the start of treatment. * Patients of childbearing age (both men and women) must use effective contraceptive methods before study entry and during the realization of it. Effective contraceptive methods for both women and men should be extended to 6 months after stopping the treatment under study. Pregnancy must be excluded by urine test (negative pregnancy test) prior to the inclusion in the study. Exclusion Criteria: * Pregnancy or breastfeeding. * Active infection or other severe concomitant diseases. * Severe psychiatric conditions that make impossible to obtain the signed informed consent form or limit the treatment compliance. * Concurrent treatment with other experimental drugs within 30 days prior to study entry. * History of previous cancer diagnosed or treated in the past 5 years except basal cell carcinoma, cervical carcinoma in situ or superficial bladder cancer.