Social Disparities Increase Breast Cancer Mortality for Black Women

Black women with breast cancer experience a nearly 40% higher mortality rate when compared with White women.¹

Despite advancements in early detection, mammography, and breast cancer therapy, Black women face a high mortality rate from breast cancer that can be attributed to several external factors. The most prominent are social determinants of health and limited studies exploring genetic differences in the presentation of breast cancer in Black women.^1,2

There are relevant studies that document the susceptibility rates and prevalence of breast cancer in Black women, but they do not explain the reason behind these findings. In a qualitative review, numerous studies concluded that Black women had significantly worse breast cancer–specific outcomes when compared with White women. More specifically, the mortality rate was 2 times higher for Black women with hormone receptor-positive (HR+) and human epidermal growth factor receptor 2–negative tumors (HER2–).³

A meta-analysis in the Journal of Clinical Oncology found a 50% higher risk of death in Black women with HR+ and HER2– tumors (relative risk [RR], 1.50; 95% CI, 1.30-1.72), 34% higher for HR+/HER2+ (RR, 1.34; 95% CI, 1.10-1.64), 20% higher for HR-/HER2+ (RR, 1.29; 95% CI, 1.00-1.43), and 17% higher among individuals with HR-/HER2- tumors (HR, 1.17; 95% CI, 1.10-1.25).¹

Yet, researchers of these studies overlooked genetic data in their findings, which may provide further insight into these disparities.

Genetic Differences Influencing Breast Cancer Mortality in Black Women

Black women are also twice as likely to develop and die from the aggressive subtype triple-negative breast cancer (TNBC). Yet, despite the drastic disparities in mortality and prognosis, the majority of genetic studies into breast cancer data have focused on women of European ancestry.⁴

However, a recent study in the journal NPJ Breast Cancer found that an increased prevalence of overall and regulatory T cells in Black women with TNBC was associated with improved survival outcomes (tumor HR, 0.46; 95% CI, 0.21-0.99; stroma HR, 0.43; 95% CI, 0.20-0.93).² On the other hand, Black women with similarly increased regulatory T cells and HER2 tumors had a hazard of death 4 times higher than those with lower levels of regulatory T cells. However, the overall T cell population was highest among women with TNBC, calling to question the relationship not only between T cells and TNBC in Black women, but also why Black women with breast cancer in general have higher levels of all 3 subtypes of T cells. The researchers emphasized how this information can be leveraged to inform and tailor treatments for this demographic.

“At present, we do not know the underlying reasons, whether biological or social, for why Black women have higher abundances of certain immune cell populations, and this is a topic for future investigation,” the authors wrote in their study on T cell subsets in Black women with invasive breast cancer.

In response to the lack of breast cancer data from Black women, a research team from Vanderbilt University sought to better understand the unique genetic risk Black women have.⁵ The study analyzed over 18,000 women of African descent who’d been diagnosed with breast cancer to conduct a genome-wide association study, specifically seeking out genetic variants often found in those with breast cancer. The analysis identified 12 genetic regions associated with breast cancer, 3 of which were linked to TNBC, and women who carried 2 genetic copies of all three loci were 4.2 times more likely to develop the aggressive subtype.

“We have worked with researchers from more than 15 institutions in the US and Africa to establish this large genetic consortium,” Zheng, lead researcher at Vanderbilt University, said in a press release with the NIH.⁶ “Data put together in this consortium have been and will continue to be used by researchers around the world.”

Social Determinants of Health and Breast Cancer Development and Treatment

Higher mortality rates and low survival outcomes among Black women can be attributed to various factors like delays in diagnosis and inadequate access to timely, quality cancer treatments, which are also impacted by social determinants of health.¹ The most relevant aspects are economic stability, access to quality health care, and the neighborhood and built environment.³

Yet, there are efforts to abate disparities in access to timely treatment. Another study sought to identify the impact Medicaid expansion had on patients with primary early-stage breast cancer.⁷ When comparing rates of delayed chemotherapy initiation before and after the expansion—in selected states—Black women experienced an absolute decrease of 3.2 percentage points.

However, despite these findings, Black women on Medicare or Medicaid and living in areas with a high neighborhood deprivation index (NDI) had significantly shorter relapse-free intervals (HR, 1.39; 95% CI, 1.0-1.84) and overall survival (HR, 1.49; 95% CI, 1.10-2.99) when compared with White women, even after adjusting for other covariates like NDI, insurance coverage, and early discontinuation of therapy.

When evaluated for contributing factors of survival disparities (demographics, comorbidities, insurance, tumor characteristics, and treatment), Black women aged 18-64 with stage I to III breast cancer had an excess mortality decrease from 105.1% to 24.9% when compared with White women, but differences in insurance status accounted for 37% of excess mortality.³ While these data suggest social determinants do play a role in survival disparities for Black women with early-stage breast cancer or HR+/HER2- breast cancer, they do not completely explain these disparities.

Combined influences of genetics and social determinants of health—more specifically, access to timely care—remain important factors when discussing the high prevalence, mortality risk, and treatment for Black women with breast cancer. While there are ongoing efforts to compile data for genetic studies to explain said disparities among Black women, further research is still needed to better equip patients with tailored chemotherapies to better address this demographic and improve outcomes.

References

1. Torres JM, Sodipo MO, Hopkins MF, Chandler PD, Warner ET. Racial differences in breast cancer survival between Black and White women according to tumor subtype: a systematic review and meta-analysis. J Clin Oncol. 2024;42(32):3867-3879. doi:10.1200/JCO.23.02311

2. Omilian AR, Mendicino L, George A, et al. Quantitative analysis of T cell subsets in a population of Black women with invasive breast cancer. Npj Breast Cancer. 2025;11(1). doi:10.1038/s41523-025-00780-5

3. Lovejoy LA, Shriver CD, Haricharan S, Ellsworth RE. Survival disparities in US Black compared to White women with hormone receptor positive-HER2 negative breast cancer. Int J Environ Res Public Health. 2023;20(4):2903. doi:10.3390/ijerph20042903

4. Gene variants and breast cancer risk in Black women. NIH. June 3, 2025. Accessed July 21, 2025. https://www.nih.gov/news-events/nih-research-matters/gene-variants-breast-cancer-risk-black-women

5. Jia G, Ping J, Guo X, et al. Genome-wide association analyses of breast cancer in women of African ancestry identify new susceptibility loci and improve risk prediction. Nat Genet. 2024;56(5):819-826. doi:10.1038/s41588-024-01736-4

6. Gene variants and breast cancer risk in Black women. News release. NIH. June 4, 2024. Accessed July 26, 2025. https://www.nih.gov/news-events/nih-research-matters/gene-variants-breast-cancer-risk-black-women

7. Chavez-MacGregor M, Lei X, Malinowski C, Zhao H, Shih YC, Giordano SH. Medicaid expansion, chemotherapy delays, and racial disparities among women with early-stage breast cancer. J Natl Cancer Inst. 2023;115(6):644-651. doi:10.1093/jnci/djad033