Racial/Ethnic Disparities in All-Cause Mortality among Patients Diagnosed with Triple-Negative Breast Cancer

Abstract

It is unclear whether racial/ethnic disparities in triple-negative breast cancer (TNBC) mortality remain after accounting for clinical characteristics, treatment, and access-to-care-related factors. In this study, women with a primary diagnosis of TNBC during 2010-2014 were identified from the National Cancer Database. Hazard ratios (HR) and 95% confidence intervals (CI) for 3- and 5-year all-cause mortality associated with race/ethnicity were estimated using Cox proportional hazards models with stepwise adjustments for age, clinical characteristics, treatment, and access-to-care-related factors. Of 78,708 patients, non-Hispanic (NH) black women had the lowest 3-year overall survival rates (79.4%), followed by NH-whites (83.1%), Hispanics (86.0%), and Asians (87.1%). After adjustment for clinical characteristics, NH-blacks had a 12% higher risk of dying 3 years post-diagnosis (HR, 1.12; 95% CI, 1.07-1.17), whereas Hispanics and Asians had a 24% (HR, 0.76; 95% CI, 0.70-0.83) and 17% (HR, 0.83; 95% CI, 0.73-0.94) lower risk than their NH-white counterparts. The black-white disparity became non-significant after combined adjustment for treatment and access-to-care-related factors (HR, 1.04; 95% CI, 0.99-1.09), whereas the white-Hispanic and white-Asian differences remained. Stratified analyses revealed that among women aged less than or equal to 50 with stage III cancer, the elevated risk among NH-blacks persisted (HR, 1.20; 95% CI, 1.04-1.39) after full adjustments. Similar results were seen for 5-year mortality. Overall, clinical characteristics, treatment, and access-to-care-related factors accounted for most of the white-black differences in all-cause mortality of TNBC but explained little about Hispanic- and Asian-white differences. SIGNIFICANCE: These findings highlight the need for equal healthcare to mitigate the black-white disparity and for investigations of contributors beyond healthcare for lower mortality among Asians and Hispanics.

Figure 1.. Multivariable-adjusted HRs (95% CI) for 3-year All-Cause Mortality in Triple Negative Breast Cancer Associated with Race/Ethnicity by Stage

The HRs and 95% CIs derived from: 0. Model 0. Adjusted for age at diagnosis (continuous). 1. Model 1. Additionally adjusted for clinical characteristics (histologic grade, histology type, tumor size, lymph node metastasis, distant metastasis, lymphovascular invasion, comorbidity). 2. Model 2. Additionally adjusted for treatment (surgery, radiation, chemotherapy, year of diagnosis and time-to-treatment) and factors related access to care (income, urban/rural residence, education, insurance, distance to care, facility type, and region of facility location). Abbreviation: HR, Hazard Ratio; CI, Confidence Interval.

Figure 2.. Multivariable-adjusted HRs (95% CI) for 3-Year All-Cause Mortality in Triple Negative Breast Cancer Associated with Race/Ethnicity by Stage and Age

The HRs and 95% CIs derived from: 1. Model 1. Additionally adjusted for clinical characteristics (histologic grade, histology type, tumor size, lymph node metastasis, distant metastasis, lymphovascular invasion, comorbidity). 2. Model 2. Additionally adjusted for treatment (surgery, radiation, chemotherapy, year of diagnosis and time-to-treatment) and factors related access to care (income, urban/rural residence, education, insurance, distance to care, facility type, and region of facility location). Abbreviation: HR, Hazard Ratio; CI, Confidence Interval.