The aims of the study were to reproduce the mP6 results and to test the efficacy of G/D in newly diagnosed, previously untreated, high-risk (HR) ES patients, in a prospective, multicentric, non-randomised study, including patients ≤40 years with ES and proved rearrangements of EWSR1. HR patients were those with pelvic or axial primary tumours, and/or metastasis, and/or BM micrometastasis. This evidence concerns the gene EWSR1 and Ewing sarcoma.