Long-Term Analysis of Patients With Ewing Sarcoma Included in the Euro-EWING99 Study

PURPOSE Euro-EWING99 study was a large, international, prospective study recruiting patients with Ewing sarcoma (EWS) between 1999 and 2015. It assessed three different clinical questions through randomized trials. We report here the characteristics and outcomes of all patients. METHODS Patients younger than 50 years with EWS were included in the study. They received induction chemotherapy (six courses of vincristine [day 1], ifosfamide [day 1-3], doxorubicin [day 1-3], and etoposide [day 1-3; VIDE], administered every 3 weeks), local therapy (surgery/radiotherapy), and different consolidation treatments according to clinical risk group and trial. The objectives of the study were to describe the entire cohort according to the initial staging group, to describe the survival outcomes (overall survival [OS]; progression-free survival [PFS]; and local control), and to evaluate prognostic factors associated with OS and PFS. RESULTS Three thousand three hundred ninety-five patients were included in the study, including 2,267 with a localized disease, 614 with pleuropulmonary metastases, and 514 with extrapulmonary metastases. Ninety-eight percent of patients received ≥4 neoadjuvant VIDE courses. The modalities of local treatment and consolidation therapy differed among the three staging groups. With a median follow-up of 7.2 years, PFS of the entire cohort was 60.2% and 55.4% at 3 and 5 years, respectively. OS was 72.6% and 64.6% at 3 and 5 years, respectively. In addition to metastatic status at diagnosis, main prognostic factors included patient age, tumor volume, and histologic response both for PFS and OS, independent of metastatic status. CONCLUSION To our knowledge, this study is the largest published series of patients with EWS and may serve as a landmark paper for EWS. It confirms the major prognostic value of the complete histologic response after neoadjuvant therapy.