Study: African Ancestry Associated With Aggressive Breast Cancer Subtypes

African genetic ancestry was found to be more strongly associated with aggressive tumor subtypes of breast cancer, according to the results of a study published in JAMA Network Open.¹ However, investigators also found that social environments were strongly associated with the survival of Black patients with breast cancer.¹

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According to a study previously published in Advances in Experimental Medicine and Biology, White women are more likely to be diagnosed with breast cancer; however, the results showed that Black women are more likely to die from the disease.²

Another key factor in mortality is poverty, the investigators noted. Women with lower economic status may not have a regular health care physician, which can affect their access to mammography screenings and increase the risk of late-stage diagnosis.²

In the current study, investigators aimed to identify the associations between African genetic ancestry, social environment, and mortality from any cause for Black individuals with breast cancer. The authors added that identifying these associations can lead to better interventions being created for this patient population.¹

The cohort study included individuals from 10 counties in New Jersey who self-identified as Black women, aged 20 to 75 years, with histologically confirmed breast cancer. Individuals were enrolled from June 2005 to May 2019, with a follow up until death or September 2021. Data were analyzed between December 2020 and April 2023.¹

The study authors used a neighborhood socioeconomic status index, which included census tract measures of education, income, wealth, employment status, and occupation. This information was linked to the residential addresses at the time of diagnosis. Investigators estimated the percentage of African ancestry using the ADMIXTURE program.¹

In total, 1575 individuals were included in the study, with a median (IQR) African ancestry of 85% and median age of 55 years. Investigators found that a 10-percentage increase of African ancestry was associated with higher odds of estrogen receptor (ER)-negative and triple-negative breast cancer (TNBC) compared to ER-positive and luminal A breast cancer, respectively. However, the study authors noted that there was not an increase with all-cause mortality or breast cancer-specific mortality.¹

Additionally, a 1-IQR increase in the neighborhood socioeconomic status was associated with lower all-cause mortality while the hazard ratio for breast cancer-specific mortality was less than 1, but not statistically significant in the age-adjusted models.¹

In a previous study by the same investigators, a lower neighborhood socioeconomic status—meaning the individuals were more disadvantaged—was associated with higher odds of TNBC, especially for neighborhoods in which there was a low representation of Black individuals.¹

Investigators said that the study findings were reduced after further adjustments for individual socioeconomic status, lifestyles, and comorbidities. However, the study authors added that helping to mediate pathways of social environments for Black individuals with breast cancer can be important for survival.¹

The study authors called for better screening interventions that focused on genetic susceptibility and population-based interventions. They emphasized a focus on access, environmental and behavioral factors to help close the gaps of racial disparities in breast cancer.¹

References

1. Iyer HS, Zeinomar N, Omilian AR, Perlstein M, et al. Neighborhood disadvantage, African genetic ancestry, cancer subtype, and mortality among breast cancer survivors. JAMA Netw Open. 2023;6(8):e2331295. doi:10.1001/jamanetworkopen.2023.31295
2. Yedjou CG, Sims JN, Miele L, Lowe L, et al. Health and racial disparity in breast cancer. Adv Exp Med Biol. 2019;1152:31-49. doi:10.1007/978-3-030-20301-6_3