Open Access

Ewa Koscielniak, Monika Sparber-Sauer, Monika Scheer, Christian Oliver Vokuhl, Bernarda Kazanowska, Ruth Ladenstein, Felix Niggli, Gustaf Ljungman, Michael Paulussen, Stefan S. Bielack, Guido Seitz, Jörg Fuchs, Erika Hallmen, Thomas Klingebiel

• Background: We have analyzed the outcome of patients with localized extraskeletal Ewing sarcoma (EES) treated in three consecutive Cooperative Weichteilsarkomstudiengruppe (CWS) soft tissue sarcoma (STS) studies: CWS-91, CWS-96, and CWS-2002P. Methods: Patients were treated in CWS-91 with four- (vincristine, dactinomycin, doxorubicin, and ifosfamide [VAIA] or cyclophosphamide [VACA II]) or five-drug (+etoposide [EVAIA]) cycles, in CWS-96 they were randomly assigned to receive VAIA or CEVAIE (+carboplatin and etoposide), and in CWS-2002P with VAIA III plus optional maintenance therapy (MT) with cyclophosphamide and vinblastine. Local therapy consisted of resection and/or radiotherapy (RT). Results: Two hundred forty-three patients fulfilled the eligibility criteria. The 5-year event-free survival (EFS) and overall survival (OS) were 63% (95% confidence interval [CI] 57–69) and 73% (95% CI 67–79), respectively. The 5-year EFS by study was 64% (95% CI 54–74) in CWS-91, 57% (95% CI 48–66) in CWS-96, and 79% (95% CI 67–91) in CWS-2002P (n.s.). The 5-year OS was 72% (95% CI 62–82) in CWS-91, 70% (95% CI 61–79) in CWS-96, and 86% (95% CI 76–96) in CWS-2002P (n.s.). In CWS-96, 5-year EFS and OS in the VAIA arm versus the CEVAIE were 65% (95% CI 52–81) versus 55% (95% CI 39–76) log-rank p = .13, and 85% (95% CI 75–96) versus 61% (95% CI 45–82), log-rank p = .09. Conclusion: Our analysis provides interesting information on the treatment and specificities of EES, which can be useful for a better understanding of this rare entity and should be considered in the development of future clinical trials for Ewing sarcoma defined as FET–ETS fusion positive tumors.