Evaluation of Racial/Ethnic Differences in Treatment and Mortality Among Women With Triple-Negative Breast Cancer

Abstract

Importance: To our knowledge, there is no consensus regarding differences in treatment and mortality between non-Hispanic African American and non-Hispanic White women with triple-negative breast cancer (TNBC). Little is known about whether racial disparities vary by sociodemographic, clinical, and neighborhood factors.

Objective: To examine the differences in clinical treatment and outcomes between African American and White women in a nationally representative cohort of patients with TNBC and further examine the contributions of sociodemographic, clinical, and neighborhood factors to TNBC outcome disparities.

Design, setting, and participants: This population-based, retrospective cohort study included 23 123 women who received a diagnosis of nonmetastatic TNBC between January 1, 2010, and December 31, 2015, followed up through December 31, 2016, and identified from the Surveillance, Epidemiology, and End Results data set. The study was conducted from July 2019 to November 2020. The analyses were performed from July 2019 to June 2020.

Exposures: Race and ethnicity, including non-Hispanic African American and non-Hispanic White race.

Main outcomes and measures: Using logistic regression analysis and competing risk regression analysis, we estimated odds ratios (ORs) of receipt of treatment and hazard ratios (HRs) of breast cancer mortality in African American patients compared with White patients.

Results: Of 23 213 participants, 5881 (25.3%) were African American women and 17 332 (74.7%) were White women. Compared with White patients, African American patients had lower odds of receiving surgery (OR, 0.69; 95% CI, 0.60-0.79) and chemotherapy (OR, 0.89; 95% CI, 0.81-0.99) after adjustment for sociodemographic, clinicopathologic, and county-level factors. During a 43-month follow-up, 3276 patients (14.2%) died of breast cancer. The HR of breast cancer mortality was 1.28 (95% CI, 1.18-1.38) for African American individuals after adjustment for sociodemographic and county-level factors. Further adjustment for clinicopathological and treatment factors reduced the HR to 1.16 (95% CI, 1.06-1.25). This association was observed in patients living in socioeconomically less deprived counties (HR, 1.26; 95% CI, 1.14-1.39), urban patients (HR, 1.21; 95% CI, 1.11-1.32), patients having stage II (HR, 1.19; 95% CI, 1.02-1.39) or III (HR, 1.15; 95% CI, 1.01-1.31) tumors that were treated with chemotherapy, and patients younger than 65 years (HR, 1.24; 95% CI, 1.12-1.37).

Conclusions and relevance: In this retrospective cohort study, African American women with nonmetastatic TNBC had a significantly higher risk of breast cancer mortality compared with their White counterparts, which was partially explained by their disparities in receipt of surgery and chemotherapy.

Figure 1.. Odds Ratios of Treatment in Non-Hispanic African American vs Non-Hispanic White Women With Triple-Negative Breast Cancer (TNBC)

The analyses were adjusted for age, health insurance, county-level socioeconomic deprivation, rural residency, cancer stage, tumor grade, tumor size, and the number of positive lymph nodes. OR indicates odds ratio.

Figure 2.. Cumulative Breast Cancer-Specific Survival in Non-Hispanic African American and Non-Hispanic White Women With Triple-Negative Breast Cancer

Figure 3.. Stage and Chemotherapy-Stratified Risk of Breast Cancer Mortality in Non-Hispanic African American vs White Patients With Triple-Negative Breast Cancer

The models were adjusted for age, type of health insurance, county-level socioeconomic deprivation, rural residency, tumor grade, surgery, and radiation therapy. HR indicates hazard ratio.