e18549 Background: Ewing sarcoma (ES) is the second most common malignant bone tumor in children and young adults. Although usually localized, subclinical metastatic disease is often present. Treatment includes multi-agent chemotherapy with surgery or radiation for local control. Though overall survival (OS) has improved to 70% for localized disease, mortality from recurrent or metastatic disease remains high. Although, ES is most common among Non-Hispanic White adolescent males, prior population-based ES studies utilizing Surveillance, Epidemiology, and End Results (SEER) have shown increased mortality among White Hispanics, Blacks, and those of low socioeconomic status (SES). Florida is not part of SEER but is home to a unique population with high proportions of immigrants and Hispanics of distinct backgrounds including Cubans, Puerto Ricans, and South Americans that contrasts to the Mexican Hispanic majority in other US states. As there are no prior population-based studies examining ES in Florida, the role of racial/ethnic disparities on outcomes among this diverse patient population remains unknown. By utilizing the Florida Cancer Data System (FCDS) for ES patients, this study will assess overall racial/ethnic disparities, evaluate the impact of racial/ethnic disparities on OS, and compare ES incidence rates in Florida with national SEER-21 rates to assess risk. Methods: This retrospective secondary analysis examined all patients diagnosed with ES (2005-2018) in Florida (n = 411) and SEER-21 (n = 1,513). Age-adjusted incidence (AAI) with 95% confidence interval (95%CI) was analyzed for the entire group and OS was estimated using Kaplan-Meier survival analysis. Univariable and multivariable analyses using Cox regression models were performed for variables of interest—race/ethnicity, age, sex, year of diagnosis, site of disease, staging, SES, and insurance type. Adjusted hazard ratio (aHR) with 95%CI were calculated. Results: Per the FCDS, there was a higher incidence of ES in Hispanic males (AAI 2.6; 95%CI: 2.0-3.2 per 1,000,000; n = 84) as compared to the SEER (1.2; 1.1-1.4; n = 250). Among non-metastatic ES, Hispanics had an increased risk for cancer-related mortality compared to Non-Hispanic Whites (aHR 2.9; 95%CI: 1.46-5.74; p =0.002), after adjusting for all other variables. In the full model (all cases regardless of stage at diagnosis), older age and distant metastasis were statistically significant factors for poor OS while SES and insurance status were not. Conclusions: Hispanics in Florida are of interest for ES with a higher-than-expected incidence compared to the US and remarkably worse survival for non-metastatic disease compared to Non-Hispanic Whites. Further in-depth studies are needed to examine why this disparity exists, but it is potentially multifactorial. This is the first known study for ES health disparities in Florida and provides updated national data for comparison.
