Assessment of Racial Disparity in Survival Outcomes for Early Hormone Receptor-Positive Breast Cancer After Adjusting for Insurance Status and Neighborhood Deprivation: A Post Hoc Analysis of a Randomized Clinical Trial

Abstract

Importance: Racial disparities in survival outcomes among Black women with hormone receptor-positive breast cancer have been reported. However, the association between individual-level and neighborhood-level social determinants of health on such disparities has not been well studied.

Objective: To evaluate the association between race and clinical outcomes (ie, relapse-free interval and overall survival) adjusting for individual insurance coverage and neighborhood deprivation index (NDI), measured using zip code of residence, in women with breast cancer.

Design, setting, and participants: This was a post hoc analysis of 9719 women with breast cancer in the Trial Assigning Individualized Options for Treatment, a randomized clinical trial conducted from April 7, 2006, to October 6, 2010. All participants received a diagnosis of hormone receptor-positive, ERBB2-negative, axillary node-negative breast cancer. The present data analysis was conducted from April 1 to October 22, 2021.

Main outcomes and measures: A multivariate model was developed to evaluate the association between race and relapse-free interval and overall survival adjusting for insurance and NDI level at study entry, early discontinuation of endocrine therapy 4 years after initiation, and clinicopathologic characteristics of cancer. Median follow-up for clinical outcomes was 96 months.

Results: A total of 9719 women (4.2% [n = 405] Asian; 7.1% [n = 693] Black; 84.3% [n = 8189] White; 4.4% [n = 403] others/not specified) were included; 9.1% of included women [n = 889] were Hispanic or Latino. Median (SD) age was 56 (9.2) years. In multivariate models, Black race compared with White race was associated with statistically significant shorter relapse-free interval (hazard ratio [HR], 1.39; 95% CI, 1.05-1.84; P = .02) and overall survival (HR, 1.49; 95% CI, 1.10-2.99; P = .009), adjusting for insurance and NDI level at study entry and other factors. Although uninsured status was not associated with clinical outcomes, patients with Medicare (HR, 1.30; 95% CI, 1.01-1.68; P = .04) and Medicaid (HR, 1.44; 95% CI, 1.01-2.05; P = .05) had shorter overall survival compared with those with private insurance. Participants living in neighborhoods in the highest NDI quartile experienced shorter overall survival compared with those in the lowest quartile (HR, 1.34; 95% CI, 1.01-1.77; P = .04), regardless of self-identified race.

Conclusions and relevance: The findings of this post hoc analysis of a randomized clinical trial suggest that Black women with breast cancer have significantly shorter relapse-free interval and overall survival compared with White women. Early discontinuation of endocrine therapy, clinicopathologic characteristics, insurance coverage, and NDI do not fully explain the observed disparity.

Trial registration: ClinicalTrials.gov Identifier: NCT00310180.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Sadigh reported receiving grants from ECOG-ACRIN pilot grant outside the submitted work. Dr Gray reported grants from US National Cancer Institute (NCI) during the conduct of the study. Dr Sparano reported grants from National Cancer Institute during the conduct of the study. Dr Yanez reported grants from Northwestern University during the conduct of the study. Dr Gareen reported grants from National Cancer Institute during the conduct of the study. Dr Whelan reported non-financial support from Genomic Health Research support outside of this submitted work. Dr Cella reported grants from NCI during the conduct of the study. Dr Wagner reported personal fees from Celgene Inc and personal fees from Athenex Inc outside the submitted work. Dr Carlos reported grants from NCI during the conduct of the study; other from JACR Salary support as editor outside the submitted work. No other disclosures were reported.

Figures

Figure.. Neighborhood Deprivation Index (NDI) Quartiles and Overall Survival by Race

The models used for the figures were unadjusted for other variables, and the power for racial comparisons within the subsets was limited. The interaction test for differences in Black vs White women across the 4 NDI groups had a nonsignificant interaction for overall survival, so the racial differences are interpreted as consistent across the NDI subsets.