Tumor Subtypes and Racial Disparities in BC

TOPLINE:

Black women in the United States have higher breast cancer (BC) mortality rates than White women across tumor subtypes. The greatest disparity in BC-specific survival was observed in hormone receptor-positive (HR+), human epidermal growth factor 2–negative (HER2−) tumors, with Black women having a 50% higher risk for death.

METHODOLOGY:

• US Black women have a 40% higher risk for death from BC than White women, and many cancer specialists believe that disparities are worse among more treatable subtypes, such as HR+ tumors.
• Researchers conducted a systematic review and meta-analysis of 18 US studies published during 2009-2022 that included 228,885 women (34,262 Black women; 182,466 White women) and examined racial differences in BC survival by subtype.
• The analysis included hormone receptor and HER2/neu status to define subtypes: HR+ HER2+, HR+ HER2−, HR− HER2+, and HR− HER2−.
• Random-effects models were used to generate pooled relative risks and 95% CI for BC-specific survival and overall survival.
• The primary outcome was BC-specific survival, with overall survival as a secondary analysis.

TAKEAWAY:

• Black women had a higher risk for BC death across all tumor subtypes than White women, with the greatest disparity observed in HR+ HER2 − tumors (hazard ratio [HR], 1.50; 95% CI, 1.30-1.72).
• The risk for BC death was also higher for Black women with HR+ HER2+ tumors (HR, 1.34; 95% CI, 1.10-1.64); HR− HER2+ tumors (HR, 1.20; 95% CI, 1.00-1.43); and HR− HER2− tumors (HR, 1.17; 95% CI, 1.10-1.25).
• Overall survival was poorer for Black women across all subtypes, although estimates for HR− HER2+ tumors did not reach statistical significance.
• In analysis of two subtypes with significant heterogeneity among studies, adjustments for socioeconomic status and number of Black participants explained about half and all the variance for HR+ HER2− and HR− HER2+, respectively.

IN PRACTICE:

“These results suggest there are both subtype-specific and subtype-independent mechanisms that contribute to disparities in breast cancer survival between Black and White women, which require multilevel interventions to address and achieve health equity,” wrote the authors. 

SOURCE:

The study was led by Juliana M. Torres, Dana-Farber/Harvard Cancer Center, CURE Program, Boston. It was published online on September 17, 2024, in Journal of Clinical Oncology.

LIMITATIONS:

The study’s limitations included potential heterogeneity between studies as indicated by significant heterogeneity in some analyses. The use of different subtype definitions and potential overlap in data sets may have also affected the results. Many included studies did not capture the extent to which treatments were completed or detection and treatment of recurrences. Additionally, the study’s findings may not fully capture socioeconomic inequality and other unmeasured factors contributing to disparities. The racial and ethnic disparities analysis focused only on Black and White women.

DISCLOSURES:

Individual authors disclosed financial relationships with Pfizer, Healthix, Merck, AstraZeneca, LabCorp, and Takeda. Additional disclosures are noted in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.