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Racial Disparities in Breast Cancer Outcomes: How Much is in the Genes?

By BCRF | May 22, 2017

New study from BCRF investigators links aggressive breast cancers to genetic differences between African American and white women.

Disparities in breast cancer outcomes among African American women compared to Caucasians and other minorities are well established. While the incidence of breast cancer is comparable between the two groups, African American women are more likely to die from their disease than white women.

African American women are more likely to be diagnosed with a more aggressive forms of breast cancer –called triple negative or basal-like – and to get cancer earlier in life than white women. These characteristics not only make their tumors more difficult to treat, but also increase the need for surveillance in younger women, education about risk, and removing the barriers to access to quality standard of care.

Studies have shown that part of this mortality gap can be attributed to differences in access to care, health insurance and other socio-economic factors. In addition, efforts are ongoing to understand the difference in the biology of breast cancer in African American women compared to whites to identify unique markers of risk and develop better treatments.

In a recently published study BCRF researchers Drs. Funmi Olopade, Charles Perou and colleagues looked at gene and protein expression and other molecular features in breast tumors from African American and white patients from The Cancer Genome Atlas. The study involved tumors from 154 African American women determined by genetic ancestry profiling and 776 white women of European descent, also determined by genetic ancestry profiling.  

The findings, published in the Journal of the American Medical Association (JAMA), could help predict breast cancer recurrences in this population as well as develop tailored interventions to improve outcomes.

“The good news is that as we learn more about these genetic variations, we can combine that information with clinical data to stratify risk and better predict recurrences – especially for highly treatable cancers – and develop interventions to improve treatment outcomes,” Dr. Olopade said.

Confirming previous reports, the authors found that African American women were more likely to have more aggressive breast cancers and poorer outcomes, while white women were more likely to have less aggressive luminal A type breast cancers.

“In the largest dataset to date with good representation of tumors from black women, we provide data showing that differences in germline genetics may be responsible for up to 40 percent of the likelihood of developing one tumor subtype versus another,” Dr. Perou said.

About 40 percent of the tumor subtyped differences were attributed to differences in germline (inherited) gene alterations between the African American and white women, suggesting a genetic link between the more aggressive tumors and ancestry in African American women. In addition, African American women had a higher PAM50 risk of recurrence score than white women, especially when comparing women in both groups who had less aggressive tumor types.

This study on disparities represents one of many that BCRF supports in our ongoing mission to understand and eradicate disparities in breast cancer care. BCRF funds research across the spectrum of the disease to reduce barriers to care, increase minority enrollment in clinical trials, increase our understanding of the unique experiences of minority women and men with breast cancer, and deep dives like this recent report from Drs. Olopade and Perou that will ultimately lead to better risk prediction and precision medicine. 

Read more about BCRF-supported research on Disparities here