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Efficacy of high dose chemotherapy in adult patients with relapsed or refractory ewing sarcoma

Background: A rare condition in adults, Ewing sarcoma (EWS) has no standard treatment during the relapse–refractory period. In our study, we aimed to identify the treatment-related side effects of high-dose chemotherapy (HDC) and salvage autologous stem cell transplantation (ASCT) in adult patients with relapsed or refractory EWS and their survival rates.
Materials and Methods: In a retrospective study, we recorded the clinical characteristics of patients with relapsed or refractory EWS treated with HDC in the hospital’s patient registry to determine their objective response rate (ORR), progression-free survival (PFS), 6-month PFS rate, overall survival (OS), 6-month OS rate, transplantation-related mortality (TRM) and treatment-related side effects.
Results: In our sample of 29 patients (72.4% male), the mean age was 26.41 years (SD = 9.35). The most common primary tumour site was the lower extremities (31%), 69% of patients had lung metastases, and 48.1% had undergone surgical resection, adjuvant radiotherapy and chemotherapy. The ORR to HDC was 31%. Median PFS (IQR) was 5.35 (6.79) months (95% confidence interval = 4.23–8.28), whereas the 6-month PFS rate was 38.9%. Median OS (IQR) was 9.46 (14.45) months (95% confidence interval = 8.52–15.82), whereas the 6-month OS rate was 68.1%. Mortality from HDC or other causes occurred in five patients within the first 100 days after ASCT. Grade 3 febrile neutropenia and thrombocytopenia were present in all patients until engraftment following ASCT. 
Conclusion: Amongst adults with relapsed or refractory EWS, HDC has successful survival and response rates and a manageable side-effects profile.