Comparison of Presentation and Management in Skeletal and Extraskeletal Ewing Sarcoma in Children

Extraskeletal Ewing sarcoma (EES) is a variant of Ewing sarcoma that originates from soft tissues rather than bones. Our study aims to characterize the differences between EES and skeletal ES (SES) in the pediatric population.

We conducted a retrospective review of children ≤ 18 years with ES recorded in the National Cancer Data Base (NCDB) from 2004 to 2022. Kaplan-Meier curves and Cox proportional hazards regression analysis were used to identify risk factors associated with survival.

Among 7446 identified patients, 1016 (20.9%) had EES and 6430 (79.1%) had SES. EES patients were older (median 14 vs. 13 years, p = 0.007), more often female (46.9% vs. 41.2%, p = 0.0009), and had smaller tumors (7.5 vs. 8.0 cm, p = 0.003). Tumor distribution differed significantly, with EES was most frequent in the thorax (49.8%) and head and neck (11.8%), while SES more common in the lower limbs (30.2%) and pelvis (25.3%) (p < 0.0001). EES patients were more likely to receive surgery alone (4.2% vs. 1.8%) or a combination of surgery, chemotherapy, and radiation (25.9% vs. 20.7%) but less likely to receive chemotherapy and radiation without surgery (19.4% vs. 29.3%, p < 0.05). Five-year overall survival was similar between SES (72.2%) and EES (73.7%) (p = 0.70). Multivariable analysis confirmed EES was not an independent predictor of survival (aHR 0.94; 95% CI 0.81-1.10). Factors independently associated with mortality were older age, metastasis at diagnosis, and positive surgical margins.

Demographic, treatment characteristics, and prognostic factors differ between pediatric patients with SES and EES. However, survival is similar between the two groups.