Black women with triple-negative breast cancer may have worse survival outcomes compared with White women, even after adjusting for external factors.
A population-based, retrospective cohort study published in JAMA Oncology showed that non-Hispanic African American women with nonmetastatic triple-negative breast cancer (TNBC) fared worse when compared with white women.1
The risk of breast cancer mortality was significantly higher for this group of women, even after adjusting for sociodemographic and county-level factors.
“Regardless of subtypes of breast cancer, many studies have shown that African American patients have lower survival than white patients,” epidemiologist and senior author Ying Liu, MD, PhD, assistant professor of surgery in the Division of Public Health Sciences at Washington University School of Medicine in St. Louis, said in a news release.2 “But there have been conflicting studies on triple-negative breast cancer outcomes. Some of these studies have shown no disparity in survival, but these were smaller studies with fewer triple-negative or African American patients. Our research uses a large study from a national dataset demonstrating that African American patients also have lower survival for this type of breast cancer. If we want to eliminate these disparities, we must first identify what they are and work to understand what drives them.”
The investigators used the Surveillance, Epidemiology, and End Results (SEER) database to identify 23,213 women who received a diagnosis of stage I to III TNBC as a first primary malignancy between 2010 and 2015. Of those, 5881 (25.3%) were African American.
Age at diagnosis was lower in African American (56.3 years) versus White (59.7 years) patients. They were also more likely to be on Medicaid (20.6% vs 8.8%), live in the most deprived counties (14.7% vs 7.1%), and reside in urban counties (92.1% vs 86.2%). Additionally, pathology tended to be more aggressive in African American women, who were more likely to present with stage III tumors (20.3% vs 15.2%), larger tumor size (>5 cm: 14.3% vs 9.6%), positive lymph nodes (39.0% vs 31.6%), and poor differentiation/undifferentiation (81.5% vs 76.0%).
African American versus White women 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) compared with White patients after adjusting for sociodemographic, clinicopathological, and neighborhood covariables. The investigators noted that there was no difference in the use of radiation therapy.
During the 46-month follow-up period, 16.8% of African American and 13.2% of White patients died from their disease, with 4.5% and 5.0% of patients, respectively, dying from other causes. This equated to a 5-year survival rate of 76.9% for African American women and 82.9% for White women included in this analysis.
After adjusting for age, insurance status, county-level socioeconomic deprivation, and rural residency, the hazard ratio for mortality in African American women was 1.28 (95% CI, 1.18-1.38). With further adjustments for clinicopathological and treatment factors, the hazard ratio was reduced to 1.16 (95% CI, 1.06-1.25). The hazard ratio for overall mortality in African American patients was 1.13 (95% CI, 1.06-1.25) after adjusting for the listed covariables.
Looking at patient subgroups, there was an increased risk of mortality in African American versus White women who were younger than 65 years (HR, 1.24; 95% CI, 1.12-1.37), those living in socioeconomically less deprived counties (HR, 1.26; 95% CI, 1.14-1.39), and those from urban areas (HR, 1.21; 95% CI, 1.11-1.32).
“There are a lot of factors beyond tumor biology that are likely contributing to these disparities,” Liu said. “Our study couldn’t measure many of these factors, but we know, for example, that African American patients are more likely to have unsatisfying communications with their doctors, experience discrimination in the health-care system, and have more difficulty with transportation to and from their appointments.”
The investigators concluded by stating that African American women experience undue burden of poor outcomes from TNBC attributable to higher disease incidence and later-stage disease and presentation. This may be aggravated by the fact that they are less likely to receive chemotherapy or surgery for their disease. Worse outcomes from TNBC were also associated with a patient’s place of residence, which may inform future studies for addressing racial disparities moving forward. Other considerations for upcoming research include tumor microenvironment, tumor biology, treatment efficacy, and access to care in African American women with TNBC.
“Some of these associations are difficult to explain because data is limited,” Liu said. “We can speculate that perhaps health care in rural or poorer communities is more difficult for cancer patients to access in general, so perhaps disparities are less apparent. But at this point, we don’t know. We will need more research to understand what factors are causing these differences in treatment and survival, so that we can find ways to address them.”
1. 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
2. Triple-negative breast cancer more deadly for African American women. News release. Washington University School of Medicine in St. Louis. May 13, 2021. Accessed May 20, 2021. https://bit.ly/3fyqkOC