Racial Disparities in Breast Cancer Characteristics and Treatment
Erin Cobain, MD, discusses findings from a study exploring the differences in diagnosis and treatment of high-risk breast cancer in Black and White patients.
Research presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting by Erin Cobain, MD, showed that Black women with hormone receptor-positive (HR+), HER2-negative (HER2–) early-stage breast cancer (EBC) face a 38% higher mortality rate than White women, a disparity not fully explained by social factors. This study, leveraging real-world data from the FLEX trial (NCT03053193), investigated whether the MammaPrint 70-gene signature accurately assesses recurrence risk across racial groups and its implications for treatment and outcomes.
Among 5142 patients analyzed (9.6% Black, 90.4% White), Black patients presented with more aggressive tumor characteristics: higher rates of node-positive disease (30.4% vs 21.9%), grade 3 tumors (25.3% vs 14.1%), and a significantly greater proportion of High 1 (43.1% vs 36.6%) and High 2 (18.3% vs 7.4%) risk classifications by MammaPrint. Despite a 61.4% incidence of high-risk disease among Black patients, only 52.9% received neo/adjuvant chemotherapy, compared to 40.3% of White patients who had a 44.0% incidence of high-risk disease. This suggests potential undertreatment of Black patients.
Crucially, the study found that clinical outcomes, specifically 4-year distant recurrence-free interval (DRFI), were comparable for similarly treated Black and White patients across MammaPrint risk groups. For instance, among chemotherapy-treated patients with High 1 tumors, DRFI was 96.0% for Black patients and 96.4% for White patients. This indicates that when Black patients receive appropriate treatment based on their MammaPrint risk classification, their outcomes are similar to White patients.
In an interview with Targeted OncologyTM, Cobain, medical oncologist at University of Michigan Rogel Cancer Center, discusses some of the potential causes for these outcomes.
"One of the potential explanations for the differences in outcome that we're observing is, is it possible that Black women are being undertreated for their high-risk breast cancer? Is it possible that despite having high molecular risk, those patients are not necessarily all receiving chemotherapy that would be indicated by standard of care?"
