Despite Black women in this country developing breast cancer at rates that are roughly 5% less than their white counterparts, they have a 40% higher mortality rate from the disease. New research suggests that race alone isn’t the biggest determining factor in cancer outcomes, but in understanding the tumors’ biology.
Last month, a new study published in Nature Partners Journal Breast Cancer led by Dr. Sonya Reid, an associate professor of medicine at Vanderbilt University and Medical Center, revealed that Black women with the most common form of breast cancer (HR+HER2) are more likely to develop more aggressive tumors that are often missed or mischaracterized as lower-risk earlier on.
“Understanding the biological and tumor genomic differences by race could improve treatment decisions and promote optimal care for Black females with early-stage breast cancer, ultimately improving long-term outcomes,” researchers wrote in the study.
Examining the data of over 1,000 women (509 Black women and 509 white women), researchers found that while there are several significant systemic factors that impact Black women’s health outcomes, they actually have a higher rate of developing basal-type tumors, one of the most aggressive forms. Meaning, what’s driving the rates may be less about race and more about genomic tests not being conducted early enough.
“While socioeconomic status – related factors contribute to worse survival outcomes, they do not fully account for survival disparities observed in Black females,” the researchers wrote.
The women in the study were matched by age and menopausal status, as researchers used genomic testing tools (MammaPrint and BluePrint) to analyze tumor genes. Rather than relying solely on traditional pathology, the tests classified cancers by genetic activity as low risk (Luminal A), moderate risk (Luminal B), and high risk (Basal-type), while also tracking cancer recurrence and survival outcomes. Through this analysis, researchers also found that genomic profiling reclassified roughly half of patients initially considered low risk based on traditional measures as having more aggressive tumors.
Compared to white women, Black women in the study were more likely to have aggressive tumor grades, greater lymph node involvement, and higher-risk genomic tumor types. For example, while 4.8% of white women had basal-type tumors, 11% of Black women did, a difference that researchers observed remained even after socioeconomic factors were corrected. Patients with high-risk tumors were also found to be five to 10 times more likely to develop distant metastases (when cancer spreads) than those with low-risk cancers, regardless of race. But most notably, when patients were compared by tumor subtype rather than race, outcomes were similar. Black women with low-risk tumors had a 97.7% 10-year recurrence-free survival rate — the same outcome seen among white women — reinforcing the researchers’ conclusion that tumor biology, not race alone, was the strongest driver of outcomes.
Researchers admit that while this study is among the first with the largest cohort of Black women with an early stage of breast cancer, there were some limitations, including the period of diagnosis for the cohorts differed, so they could not match based on year of diagnosis. The study also lacked data on treatment adherence, social determinants of health, and detailed comorbidity information, all of which, they explain, may contribute to observed outcome differences and could not be accounted for in the analyses. This analysis was further limited to participants who self-identified as Black or white; thus, outcomes in other racial or ethnic groups were not evaluated.
Regardless, based on the study, women, especially Black women, would benefit from genomic testing earlier, which could help identify aggressive cancers earlier, which in turn could guide better treatment decisions and begin to reduce the racial disparity.
“Despite advancements in treatment options to improve breast cancer outcomes, socioeconomic factors, such as later stage at diagnosis and lack of access to genomic testing, continue to contribute to racial survival disparities,” the researchers explained. “However, socioeconomic factors alone are unlikely to fully account for survival disparities observed among Black females.”
