A Comparison of Osseous and Extraosseous Ewing Sarcoma.

Objective: To compare the clinicopathological characteristics, treatment responses, survival analysis of osseous Ewing sarcoma (OES) and extraosseous ES (EES).

Study Design: Observational study.

Place And Duration Of Study: Ankara City Hospital and Ankara Numune Training Research Hospital Medical Oncology Clinics from January 2005 to February 2020.

Methodology: Clinicopathological characteristics of histologically confirmed ES/PNET and followed up, and treatment modalities were recorded from patients' registration data-base of the hospital. Lactate dehydrogenase (LDH), alkaline phosphatase (ALP), hemoglobin were measured before chemotherapy or surgery. The patients with a second cancer, gall bladder/biliary tract diseases, viral hepatitis and other bone diseases were excluded.

Results: Sixty seven patients evaluated retrospectively. Out of the total patients, 56.7% consisted of OES, and 43.3% consisted of EES. The median age of the EES group (26 years) was significantly higher than that of the OES group (22 years, p = 0.008). The most common metastasis region was lung in both the groups. Age, LDH levels and stage of the disease were found to be statistically significant prognostic factors in univariate and multivariate analysis. The median OS of patients who started with local treatment (surgical, surgical ± radiotherapy) and followed up with chemotherapy was 82.6 months (95% CI, 55.2-110.1), while the median OS of patients who received local treatment between or after chemotherapy was 43.4 months (95% CI, 13.2-73.6, p = 0.042).

Conclusion: Patients with extrosseus ES were significantly older. Age, LDH levels, stage of disease, local treatment followed by systemic therapy are important associated factors. Key Words: Osseous ewing sarcoma, Extraosseous ewing sarcoma, Chemotherapy, Local treatment.