Ewing sarcoma demonstrates racial disparities in incidence-related and sex-related differences in outcome: an analysis of 1631 cases from the SEER database, 1973-2005

Abstract

Background: Previous reports of Ewing sarcoma cohorts suggested that there is a difference in incidence according to racial origin. However, to the authors' knowledge, this finding has never been tested in a population-based database, and the impact of race on clinical outcome and the significance of known risk factors stratified to racial groups have not been reported.

Methods: Patients who had Ewing sarcoma diagnosed between 1973 and 2005 were identified in the Surveillance, Epidemiology, and End Results database. Patient demographic and clinical characteristics; incidence; year of diagnosis; tumor location, tumor size, and disease stage at diagnosis; treatment(s); cause of death; and survival were extracted. Kaplan-Meier, log-rank, and Cox regressions were used to analyze the significance of prognostic factors.

Results: Race-specific incidence indicated that Caucasians have the highest incidence (0.155), followed by Asians/Pacific Islanders (0.082), and African Americans (0.017). The difference in incidence between Caucasians and African Americans was 9-fold and significant (P<.001). The incidence of Ewing sarcoma increased over the past 3 decades among Caucasians (P<.05). Survival was not impacted by race. Local disease stage, primary tumor location in the appendicular skeleton, and tumor size<or=8 cm conferred a significant survival benefit. Women demonstrated improved survival among the Caucasian patients (P<.03).

Conclusions: To the authors' knowledge, this is the first report focusing on racial disparity in incidence of Ewing sarcoma. Caucasians were affected more frequently, although outcomes were similar between races. It is noteworthy that being a woman constituted a survival benefit only among the Caucasian patients. Further studies will need to clarify the reasons for racial disparities in incidence and for sex differences in survival.