Disparities in adjuvant treatment between Black and White women with endometrial cancer exist and contribute to worse outcomes among Black women. However, factors leading to disparate treatment receipt are understudied.

We examined whether patient refusal of adjuvant treatment (chemotherapy or radiation) differed between Black and White women and whether treatment refusal mediated racial disparities in survival among women with endometrial cancer.

We used the National Cancer Database, a hospital-based cancer registry, to identify non-Hispanic Black and non-Hispanic White women diagnosed with endometrial cancer from 2004 to 2016 who either received or refused recommended radiation or chemotherapy. We used logistic regression to estimate multivariable-adjusted odds ratios and 95% confidence intervals for associations between race and treatment refusal. We also examined predictors of treatment refusal in race-specific models. Accelerated failure time models were used to estimate absolute differences in overall survival by race. We used causal mediation analysis to estimate the proportion of racial differences in overall survival attributable to racial differences in adjuvant treatment refusal. We considered the overall study population and strata defined by histology, and adjusted for sociodemographic, tumor, and facility characteristics.

Our analysis included 75,447 endometrial cancer patients recommended to receive radiation and 60,187 endometrial cancer patients recommended to receive chemotherapy, among which 6.4% and 11.4% refused treatment, respectively. Among Black women recommended for radiation or chemotherapy, 6.4% and 9.6% refused, respectively. Among White women recommended for radiation or chemotherapy, 6.4% and 11.8% refused, respectively. After adjusting for sociodemographic variables, facility characteristics, and tumor characteristics, Black women were more likely to refuse chemotherapy than White women (adjusted odds ratio, 1.26; 95% confidence interval, 1.15–1.37), but no difference in radiation refusal was observed (adjusted odds ratio, 1.00; 95% confidence interval, 0.91–1.11). Some predictors of radiation refusal varied by race, namely income, education, histology, stage, and chemotherapy receipt (P interactions<.05), whereas predictors of chemotherapy refusal were generally similar between Black and White women. Among women recommended for radiation, Black women survived an average of 4.3 years shorter than White women, which did not seem attributable to differences in radiation refusal. Among women recommended for chemotherapy, Black women survived an average of 3.2 years shorter than White women of which 1.9 months (4.9%) could potentially be attributed to differences in chemotherapy refusal.

We observed differences in chemotherapy refusal by race, and those differences may be responsible for up to about 2 months of the overall 3.2-year survival disparity between White and Black women. Radiation refusal did not explain any of the 4.3-year disparity among women recommended for radiation. Treatment refusal accounts for, at most, a small fraction of the total racial disparity in endometrial cancer survival. Although a better understanding of the reasons for patient treatment refusal and subsequent intervention may help improve outcomes for some women, other causes of disparate outcomes, particularly those reflecting the social determinants of health, must be investigated.