Abstract A087: Racial and ethnic disparities in endometrial cancer survival: The mediating role of guideline-concordant treatment

Abstract

Receipt of guideline-concordant treatment is associated with improved survival among patients with endometrial cancer, and racial and ethnic disparities in receipt of guideline-concordant care are well established. However, the extent to which guideline-concordant treatment disparities contribute to racial and ethnic survival differences remains unknown. We conducted a retrospective cohort study of patients diagnosed with endometrial cancer between 2010 and 2019 using the National Cancer Database. American Indian/Alaska Native (AI/AN), Asian, Black, Hispanic, Native Hawaiian/Pacific Islander (NH/PI), and White patients were included. Guideline-concordant treatment was defined by comparing observed treatment with National Comprehensive Cancer Network (NCCN) recommendations based on year of diagnosis, stage, histology, and grade, while incorporating treatment adequacy metrics, including timely initiation, radiation fractions, and completion within expected treatment durations. We estimated total associations between race/ethnicity and overall survival and decomposed these associations using counterfactual-based causal mediation analysis. Guideline concordant treatment was modeled using logistic regression, and overall survival was modeled using Weibull accelerated failure time models to estimate natural direct and indirect effects. Models adjusted for sociodemographic, tumor, and facility-level confounders. Among 145,227 patients, guideline-concordant treatment was lower among Black (OR=0.77, 95% CI=0.74, 0.81) and Hispanic (OR=0.77, 95% CI=0.73, 0.81) as compared with White patients but did not differ for AI/AN, Asian, and NH/PI patients. In adjusted models, compared with White patients, Black patients experienced substantially shorter mean survival (-127.0 months; 95% CI=−146.2, −106.5) as did NH/PI patients (-134.7 months; 95% CI=-226.7, -21.3), while Hispanic (+122.9 months; 95% CI= 78.1, 172.4) and Asian patients had improved survival (+192.4 months; 95% CI= 125.0, 268.6). Survival differences for AI/AN patients were smaller and imprecise. Mediation analyses indicated that the differences in guideline-concordant treatment explained a modest proportion of the Black-White survival disparity (average causal mediation effect [ACME]: -7.3 months; 95% CI=-8.8, -5.8), corresponding to 5.8% of the total effect (p<0.001). For Hispanic patients, guideline-concordant treatment differences had a similar relationship with survival (ACME: -7.2 months; 95% CI=-9.1, -5.5; proportion mediated: -5.9%; p<0.001), suggesting that equalizing treatment would further improve their observed survival advantage. Differences in receipt of guideline-concordant treatment represent one pathway linking race/ethnicity to survival in endometrial cancer, although they do not fully account for observed disparities. Even if not fully explanatory of survival differences, inequities in receipt of guideline-concordant care represent a critical and modifiable manifestation of structural inequity in cancer care delivery. Ashley S. Felix, Simran A. Kanal, Caitlin E. Meade, Jennifer A. Sinnott. Racial and ethnic disparities in endometrial cancer survival: The mediating role of guideline-concordant treatment [abstract]. In: Proceedings of the 19th AACR Conference on the Science of Cancer Health Disparities; 2026 Oct 18-21; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2026;35(10 Suppl):Abstract nr A087.