African-American patients with nonmetastatic triple-negative breast cancer (TNBC) have a higher risk of death than their White counterparts, and this is partially explained by treatment differences, according to researchers. They reported their findings in JAMA Oncology.
The retrospective study included 23,123 patients with nonmetastatic TNBC who were enrolled in the Surveillance, Epidemiology, and End Results (SEER) database. A total of 17,332 (74.7%) patients were White, and 5881 (25.3%) were African American.
The African-American patients were younger at diagnosis (56.3 years vs 59.7 years), and their disease was pathologically more aggressive, with larger tumor size, positive lymph nodes, and poor differentiation.
In the overall cohort, a majority of patients had undergone surgery (94.7%), chemotherapy (74.5%), and/or radiotherapy (51.9%).
The African-American patients had lower odds of receiving surgery (odds ratio [OR], 0.69; 95% CI, 0.60-0.79) and chemotherapy (OR, 0.89; 95% CI, 0.81-0.99) compared with their White counterparts. However, there was no significant difference between the groups in receipt of radiotherapy.
During a median follow-up of 43 months, 3276 (14.2%) patients died from breast cancer. The 5-year survival rate was lower among the African-American patients than among the White patients — 76.9% and 82.9%, respectively.
The African-American patients had a higher risk of breast cancer mortality after adjustment for age, insurance status, county-level socioeconomic deprivation, and rural residency (hazard ratio [HR], 1.28; 95% CI, 1.18-1.38). That risk decreased after adjustment for clinicopathological and treatment factors (HR, 1.16; 95% CI, 1.06-1.25).
“The association between race and breast cancer mortality significantly varied by age at diagnosis, county-level socioeconomic deprivation, and rural/urban residency,” the study authors noted.
The increased breast cancer mortality risk in African-American patients was observed in those younger than 65 years (HR, 1.24; 95% CI, 1.12-1.37) but not in older patients, those living in socioeconomically less deprived counties (HR, 1.26; 95% CI, 1.14-1.39) but not in more deprived counties, and those from urban areas (HR, 1.21; 95% CI, 1.11-1.32) but not rural areas.
In fact, African-American patients living in rural areas had a lower risk of breast cancer death than their White counterparts (HR, 0.72; 95% CI, 0.53-0.96). This finding warrants additional studies to explain the association between race and TNBC outcomes in rural and urban areas, according to the study authors.
“Improving treatment adherence and efficacy in African-American women with TNBC is crucial in reducing TNBC disparities,” the authors concluded. “Future studies that focus on tumor microenvironment, tumor biology, treatment efficacy, and access to care in African-American women with TNBC could advance understanding of the drivers of TNBC outcome disparities and complement a deeper understanding of social factors.”
Cho B, Han Y, Lian M, et al. Evaluation of racial/ethnic differences in treatment and mortality among women with triple-negative breast cancer. JAMA Oncol. Published online May 13, 2021. doi:10.1001/jamaoncol.2021.1254