Ewing sarcoma of the hands and feet: Outcome and prognostic factors of a rare subsite in a low-middle income country

The small bones of the hand and feet represent a rare site of Ewing sarcoma (ES) origin. This study presents a real-world dataset describing the clinical presentation, survival outcomes, and their determinants in this subsite. This is a single-institutional retrospective study of patients with ES originating from the hands/feet (ES-HF), treated between 2003-2018. Clinical/demographic details and survival outcomes were retrieved from medical records. Descriptive statistics were used to summarize baseline characteristics. Prognostic factors for event-free survival (EFS) and overall survival (OS) were identified by Cox regression. The clinical features and outcomes were compared between ES-HF and ES-others (ES from other sites) in the cohort. Of 859 ES cases, 28 (3.2%) patients had ES-HF including four ES-hands (0.5%) and 24 ES-feet (2.8%). The calcaneum was the most common site [11 of 28 cases; 39.3%]. More than half of the patients (53.6%) had metastatic disease at presentation. In comparison with ES-others, ES-HF had longer median symptom duration [12 versus 4 months; p<0.001] and smaller tumor diameter [5.5 versus 9 cm; p<0.001]. The median EFS and OS of the cohort were 30.5 and 39.13 months respectively. Only local therapy receipt was associated with improved EFS (multivariable HR:0.013; 95%CI:0.001-0.158; p<0.001) and OS (multivariable HR:0.028; 95%CI:0.003-0.272; p=0.002). Patients receiving radiotherapy alone had inferior OS compared to those receiving surgery alone. (HR: 9.22; 95% CI: 1.12-76.31; p=0.039) ES-HF is a rare ES subsite. Although indolent, metastases are common at presentation. Meticulous local control can improve survival in both localized and metastatic disease.