Social factors, tumor biology equally linked to racial disparity in breast cancer survival
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Black women with ER-positive, early-stage breast cancer appeared at significantly higher risk for death than their white counterparts, according to study results published in JAMA Oncology.
Structural and individual disadvantage contributed to the survival disparity just as much as aggressive tumor biology, researchers noted.
Rationale and methodology
Adverse social determinants of health concentrated in Black communities have long been recognized as root causes of worse breast cancer outcomes for Black women, Kent F. Hoskins, MD, associate division chief for hematology and oncology at University of Illinois at Chicago, told Healio.
“Health disparities research has primarily focused on the higher prevalence of late-stage diagnoses and the aggressive triple-negative breast cancer subtype among Black women,” Hoskins said. “Earlier work from our group and others showed significant survival disparities among Black women who have the more common hormone receptor-positive breast cancer subtype, even after controlling for stage at diagnosis and treatment, which suggests that tumor biology may play a role.”
An earlier study his team conducted confirmed this hypothesis, he said.
“That study showed Black women with early-stage, hormone receptor-positive tumors were 30% more likely to have a high-risk score on prognostic gene expression test,” Hoskins said. “That finding led to the question that we addressed in this study, which is how much does disproportionately aggressive tumor biology contribute to worse breast cancer survival for Black women with early-stage, hormone receptor-positive tumors?”
Hoskins and colleagues pooled data on 60,137 women (mean age, 58.1 years) included in the SEER-Oncotype Dx Database between 2004 and 2015 with follow-up through 2016. They sought to examine the proportion of disparities in breast cancer survival among Black (n = 5,648) vs. white women (n = 54,489) with ER-positive, axillary node-negative breast cancer who had an available 21-gene breast recurrence score.
Median follow-up was 56 months.
Findings
Results showed an age-adjusted HR of 1.82 (95% CI, 1.51-2.2) for breast cancer death among Black vs. white women.
Insurance status and neighborhood disadvantage accounted for 19% of the disparity (mediated HR = 1.62; 95% CI, 1.31-2), whereas tumor biology accounted for 20% (mediated HR = 1.56; 95% CI, 1.28-1.9).
“Measures of structural disadvantage, including census tract income, poverty and education, as well as individual disadvantage, indicated by having public aid health insurance, accounted for approximately the same proportion of the racial disparity as having higher scores on the Oncotype gene expression profile, tumor grade and absence of progesterone receptor expression,” Hoskins said.
Results of a fully adjusted model additionally showed that all covariates accounted for 44% of racial disparity (mediated HR = 1.38; 95% CI, 1.11-1.71). Neighborhood disadvantage accounted for 8% of the racial difference in the probability of a high-risk recurrence score (P = .02).
Implications
Oncologists should be aware that Black women are more likely to have biologically aggressive forms of hormone receptor-positive breast cancer and should take that into account in treatment planning, Hoskins told Healio.
“The findings underscore the need for hospitals and oncology clinics to develop clinical programs, such as patient navigation, that can help mitigate the deleterious effects of social disadvantage on cancer care because that is a major driver of worse outcomes for Black women,” he said.
The data also point to a double imperative for future research to identify underlying molecular mechanisms that are driving disproportionately aggressive tumor biology among Black women so that effective targeted therapies can be developed, Hoskins continued.
“Future research is needed to determine the multilevel effects of social disadvantage on cancer care among Black women so that strategies and policies can be implemented to overcome the negative effects of social disadvantage and structural racism on cancer care,” he said.
References:
- Breast cancer disparity equally impacted by social determinants of health, tumor biology (press release). Available at: today.uic.edu/breast-cancer-disparity-equally-impacted-by-social-determinants-of-health-tumor-biology. Published Feb. 16, 2023. Accessed Feb. 21, 2023.
- Hoskins KF, et al. JAMA Oncol. 2023;doi:10.1001/jamaoncol.2022.7705.
For more information:
Kent F. Hoskins, MD, can be reached at khoski@uic.edu.
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