Soft-Tissue Ewing Sarcoma in a Low-incidence Population: Comparison to Skeletal Ewing Sarcoma for Clinical Characteristics and Treatment Outcome

Objective: Due to the low incidence, treatments for Korean soft tissue Ewing sarcoma patients have been heterogeneous, and reported data are limited. In this study, we retrospectively analyzed soft tissue Ewing cases treated at our institution. Methods: We analyzed the clinicopathologic characteristics and treatment outcome of soft tissue Ewing sarcoma patients and compared with those of skeletal cases. Results: Twenty-seven soft tissue Ewing sarcoma cases were evaluated. Patients with soft tissue Ewing sarcoma were older than patients with skeletal tumors (P ¼ 0.03), and tended to have metastasis at diagnosis (P ¼ 0.12). However, sex ratios, pathologies, tumor volumes, and histologic response to preoperative chemotherapy were not different in the two groups. The 5-year overall survival (49.0%) and event-free survival (45.6%) of soft tissue Ewing sarcoma patients were similar to those of skeletal tumor patients (51.8% and 46.0%, respectively). Presence of metastasis at diagnosis and poor histologic response to preoperative chemotherapy were associated with an adverse outcome for both groups. Similar to skeletal tumors, central tumor location, pathology and tumor volume tended to be related to the survival of soft tissue Ewing sarcoma. However, age and the use of a modality other than surgery to achieve local control did not influence the survival of soft tissue Ewing sarcoma patients. Conclusions: Our data could provide a basis to design a collaborative or multinational study targeting Ewing sarcoma family tumors.