(P 296) DISPARITIES IN OVERALL SURVIVAL FOR AYA PATIENTS WITH EWINGS SARCOMA: A RETROSPECTIVE COHORT STUDY AT A SINGLE SARCOMA CENTER

Objective: Ewing sarcoma (ES) is a highly aggressive tumor and ranks as the second most common primary bone malignancy in adolescents and young adults. It predominantly affects non-Hispanic Whites (NHW), but the incidence is rising among Hispanics. Studies using the Surveillance, Epidemiology, and End Results (SEER) program indicate higher all-cause mortality among White Hispanics, Blacks, and low socioeconomic status (SES) individuals. Florida, not included in SEER, has a diverse Hispanic population (Cubans, Puerto Ricans, South Americans) compared to the predominantly Mexican Hispanic populations in other U.S. states. The Florida Cancer Data System found higher ES incidence among Hispanic males in Florida and worse survival rates for nonmetastatic osseous disease among Hispanics compared to NHWs, highlighting the need for further research into these disparities.

Adolescent and young adult (AYA) patients aged 15 to 39, account for 7% of all new U.S. cancer cases, and 30% of Ewing Sarcoma and have not seen the same survival rate improvements as other age groups over the past 30 years. This study aimed to evaluate ethnic disparities in survival outcomes among AYA individuals diagnosed with Ewing sarcoma.

Methods: We performed a retrospective cohort study of patients with biopsy proven Ewings sarcoma. Our study examined patients between the ages 15-39 years diagnosed with Ewings sarcoma (2005–2024) at the University of Miami Sylvester Cancer Center (n=45). Demographics including sex, ethnicity, age, and age at diagnosis were collected from the electronic medical records. Additional variables that were gathered include primary tumor location/characteristic (extraosseous vs. osseous), treatment type, treatment intent, and treatment timeline. Kaplan-Meier curves and logistic regression models were employed for survival analysis, with adjustments for confounding variables. Statistical analyses were conducted using R Studio, with a significance threshold set at p< 0.05. The study was approved by the Institutional Review Board at the University of Miami.

Results: There is a significant difference in overall survival between NHW patients and Hispanic patients (p=0.018), with NHW individuals showing higher overall survival rates compared to Hispanics (Figure 1). Logistic regression analysis revealed that Hispanics were more likely to have extraosseous involvement, while NHW were more likely to have osseous disease (p-value = 0.0375, 95% CI: 1.132 - 17.829). On further review, the Kaplan-Meier survival curves for patients with extraosseous disease (p = 0.059) and osseous disease (p = 0.25) both indicate that NHW patients have higher overall survival rates compared to Hispanic patients, though neither difference is statistically significant (Figure 2,3). The trend towards better survival in non-Hispanic patients is more pronounced in the extraosseous group compared to the osseous group.

Other notable findings, though not statistically significant, include NHW patients tend to be older and less likely to have metastatic disease at diagnosis, more frequently undergo surgery, with higher curative intent and lower rates of recurrence. Hispanic patients more often have tumors in extremities, receive systemic treatments, and have higher palliative treatment intent (Table 1).

Conclusion: There was a notable disparity in overall survival between NHW and Hispanic patients with Ewings sarcoma in the AYA age group. Hispanics were more likely to have extraosseous disease, while NHW had osseous. Although Kaplan-Meier survival curves for both extraosseous and osseous diseases suggest better survival for NHW patients, these differences are not statistically significant, and could be attributed to the small sample size of this study. Further investigation into hereditary factors, environmental exposures, lifestyle, SES, and psychosocial factors is needed to understand and address these disparities, improving survival rates and quality of life.