Characteristics and outcomes of patients with Ewing sarcoma over 40 years of age at diagnosis

Background: The peak incidence of Ewing sarcoma (EWS) is in adolescence, with little known about patients who are ≥40 years at diagnosis. We describe the clinical characteristics and survival of this rare group. Methods: This retrospective cohort study utilized the Surveillance Epidemiology and End Results database. 2780 patients were identified; including 383 patients diagnosed ≥40 years. Patient characteristics between age groups were compared using chi-squared tests. Survival from diagnosis to death was estimated via Kaplan-Meier methods, compared with log-rank tests, and modeled using multivariable Cox methods. A competing risks analysis was performed to evaluate death due to cancer. Results: Patients ≥40 years of age were more likely to have extra-skeletal tumors (66.1% vs. 31.7%; p < 0.001), axial tumors (64.0% vs. 57.2%; p = 0.01), and metastatic disease at diagnosis (35.5% vs. 30.0%; p = 0.04) compared to younger patients. Five-year survival for those age ≥40 and age <40 were 40.6% and 54.3%, respectively (p < 0.0001). A Cox multivariable model controlling for differences between groups confirmed inferior survival for older patients (hazard ratio for death of 2.04; 95% CI 1.63-2.54; p < 0.0001); though treatment data were unavailable and not controlled for in the model. A competing risks analysis confirmed increased risk of cancer-related death in older patients. Conclusion: Patients ≥40 years at diagnosis with EWS are more likely to have extra-skeletal tumors, metastatic disease, and axial primary tumors suggesting a difference in tumor biology. Independent of differences in these characteristics, older patients also have a lower survival rate.