Outcomes of extraskeletal vs. skeletal Ewing sarcoma patients treated with standard chemotherapy protocol

To compare the outcomes of extraskeletal and skeletal Ewing sarcomas treated with standard chemotherapy protocol.

We retrospectively collected data on primary localized skeletal and extraskeletal ES patients. Demographics and disease characteristics were compared between the two groups. The influence of presentation (skeletal vs. extraskeletal) on overall survival (OS) and local recurrence-free survival (LRFS) was assessed and compared by the log-rank test.

A total of 120 patients were included; 29 (24%) had extraskeletal and 91 (76%) had skeletal ES. All patients received vincristine, doxorubicin, and cyclophosphamide alternating with ifosfamide and etoposide (VDC-IE) chemotherapy, with a plan for local control at week 12. At a median follow-up of 38 months, there was no difference in OS between skeletal and extraskeletal ES; 5-year OS 70% and 67% respectively, p = 0.96. Patients with extraskeletal ES had inferior 5-year LRFS compared to skeletal ES; 74% vs. 83%; p = 0.042. Local recurrence occurred at a higher frequency in the extraskeletal group; 28% vs. 11%, p = 0.034, although more extraskeletal patients received adjuvant radiotherapy; 73% vs. 36%, p = 0.01. Among patients who underwent surgery (n = 76), there was no difference in R0 resection rate (skeletal: 89%, extraskeletal: 86%, p = 0.52, or good ( ≥ 90%) tumor necrosis; skeletal: 54%, extraskeletal: 38%, p = 0.31.

Patients with localized extraskeletal ES have comparable OS outcomes to patients with skeletal ES utilizing the standard VDC-IE chemotherapy. However, extraskeletal patients are at significantly higher risk for local recurrence.