More than treatment refusal: an NCDB analysis of the impact of endometrial cancer treatment refusal on racial survival disparities

Abstract

<h3>Objectives:</h3> Disparities in adjuvant treatment between Black and White women with endometrial cancer (EC) are well documented and contribute to worse outcomes among Black women. However, factors leading to disparate treatment patterns are understudied. We examined whether patient refusal of adjuvant treatment (chemotherapy or radiation) differed between Black and White women and whether refusal differences mediate racial disparities in EC survival. <h3>Methods:</h3> We used the National Cancer Database (NCDB), a hospital-based registry covering ~70% of U.S. cancer diagnoses, to identify non-Hispanic Black (NHB) and non-Hispanic White (NHW) women diagnosed with EC from 2004 to 2015 who either received or refused chemotherapy or radiation. NCDB data are abstracted from medical records by tumor registrars. We used logistic regression to estimate adjusted odds ratios (aOR) of patient refusal of treatment associated with race, and accelerated failure time models to estimate differences in overall survival (OS) by race. We used causal mediation analysis to estimate how much of the difference in OS by race could be attributed to racial differences in treatment refusal. We considered the overall study populations as well as strata defined by histology, and adjusted for factors assessed at diagnosis, including age, comorbidity burden, insurance, hospital characteristics, stage, histology, and zip code-level income and education. <h3>Results:</h3> We identified 49,518 women (83% NHW, 17% NHB) who received adjuvant chemotherapy and 12,710 women with documented refusal (90% NHW, 10% NHB). After adjusting for covariates, NHB women were more likely to refuse chemotherapy than NHW women (aOR=1.12, p=0.005), particularly among those with low-grade endometrioid (aOR = 1.22, p=0.02) or serous (aOR = 1.38, p<0.001) EC. Mean OS for NHB women was 43.5 months shorter than for NHW women. Of this disparity, 0.9 months of may be attributable to differences in chemotherapy refusal (p=0.01). Among women with serous EC, NHB race was associated with 17.6 months shorter OS, with 1 month potentially attributable to refusal differences (p=0.002). We identified 66,839 women (88% NHW, 12% NHB) receiving adjuvant radiation and 4,471 (88% NHW, 12% NHB) who refused. Among women with serous EC, NHB women were more likely to refuse radiation (OR = 1.39, p=0.01), and NHB women had mean OS 13.2 months shorter than NHW women, 0.4 months of which may be attributable to differences in treatment refusal (p=0.03). <h3>Conclusions:</h3> We observed differences in treatment refusal by race, and those differences may be responsible for up to 1 month of the OS disparity between NHW and NHB women. This represents a small fraction of the dramatic racial disparity in EC survival. While 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 warrant further investigation.