Racial/ethnic inequities in care for patients with advanced endometrial cancer: What’s structural racism and social determinants of health got to do with it?

1602 Background: Structural racism and social determinants of health (SDOH) have been linked to inequities in cancer care and outcomes. However, little is known about the contribution of such factors to care inequities among patients with endometrial cancer, where Black women experience a nearly two-fold increased risk of death relative to their White counterparts. We examined the role of structural racism and SDOH in explaining racial/ethnic inequities in care for patients with advanced endometrial cancer (aEC). Methods: This retrospective study used the nationwide Flatiron Health electronic health record (EHR)-derived de-identified database, focusing on patients diagnosed with aEC from January 2013 to September 2023 (follow-up through December 2023). Outcomes included time-to-treatment initiation, use of immunotherapy or targeted therapy, biomarker testing, and clinical trial participation. We estimated a series of multivariable Cox proportional hazards models assessing racial/ethnic inequities in outcomes, sequentially adjusting for clinical factors (e.g., age, stage at diagnosis) followed by structural racism (residential segregation) and SDOH factors (e.g., insurance, practice setting, area-level vehicle ownership). Results: The cohort included 5,496 patients (2.2% Asian, 14.8% Black, 5.2% Latinx, 61.4% White, and 16.0% Other/Unknown). Although diagnosed with more aggressive disease (37% vs. 21% serous carcinoma), Black patients were less likely than White patients to initiate treatment during follow-up (hazard ratio HR=0.91 95% CI: 0.83-0.99), participate in a clinical trial (HR=0.56 95% CI: 0.38-0.84), and receive biomarker testing (HR=0.88 95% CI: 0.81-0.97). Compared with their White counterparts, Latinx patients were less likely to participate in a clinical trial (HR=0.41 95% CI: 0.19-0.87). Black-White (HR=0.80 95% CI: 0.47-1.38) and Latinx-White (HR=0.71 95% CI: 0.31-1.60) inequities in clinical trial participation were partly explained by structural racism and SDOH factors, while Black-White inequities in treatment and biomarker testing remained largely unchanged following structural and social determinants adjustment. We saw no racial/ethnic differences in use of immunotherapy or targeted therapy. Conclusions: We observed racial/ethnic inequities in treatment initiation, biomarker testing, and clinical trial participation among patients with aEC, with structural racism and SDOH substantially accounting for inequities in trial participation. Thus, findings from this study suggest that efforts aimed at improving diversity in endometrial cancer trials, and overall equity in endometrial cancer outcomes, should prioritize mitigating the structural and social barriers to clinical trial participation.