Racial Disparities in Treatment and Outcomes for Hormone Receptor–Positive/HER2-Negative Metastatic Breast Cancer

A recent US-based study examined racial disparities in biomarker prevalence, treatment patterns, and clinical outcomes among Black and White patients with hormone receptor (HR)-positive/HER2-negative metastatic breast cancer (mBC) who underwent next-generation sequencing (NGS). The study utilized data from the Flatiron Health–Foundation Medicine Clinico-Genomic Database, a nationwide, deidentified electronic health record database.

The study included 2384 patients diagnosed with HR-positive/HER2-negative mBC between January 2017 and March 2022, with 12.7% (303) of patients identifying as Black and 87.3% (2081) as White. The median time from mBC diagnosis to the first NGS testing was comparable in both groups (4.6 vs 4.9 months; P=.12). The research focused on the prevalence of alterations in the following biomarkers: PIK3CA, AKT1, PTEN, ESR1, and BRCA1/2. Black patients demonstrated a notably lower prevalence of PIK3CA mutations compared with White patients (34% vs 42%; P=.03), but no significant differences were found in the prevalence of the other biomarkers between the 2 groups.

A key aspect of the study was the analysis of treatment patterns in both groups; 2191 patients received first-line treatment, with 90% of Black patients and 92% of White patients receiving first-line treatment. A significant disparity emerged in the use of CDK4/6 inhibitors, a standard first-line therapy for HR-positive/HER2-negative mBC. In first-line treatment, Black patients were less likely to receive CDK4/6 inhibitors compared with White patients (53% vs 66%; P<.001). Conversely, Black patients were more likely to receive chemotherapy as a first-line treatment compared with White patients (27% vs 18%; P<.001). Even after adjusting for baseline characteristics, the odds of receiving first-line CDK4/6 inhibitors was significantly lower for Black patients compared with White patients (odds ratio, 0.62; 95% confidence interval [CI], 0.48-0.81; P<.001). However, in the second-line setting, where treatment choices depend on various clinical and biomarker factors, the use of CDK4/6 inhibitors and chemotherapy was similar between Black and White patients. Importantly, among patients with PIK3CA mutations receiving second-line therapy, there was no significant difference in the use of PI3Kα-specific inhibitors between Black and White patients (34% vs 26%; P=.40).

The study also examined the overall survival (OS) of patients from the time of mBC diagnosis. A statistically significant difference in median OS was observed, with Black patients experiencing shorter OS compared with White patients (34.1 vs 42.1 months; P=.004). This difference in OS persisted even after adjusting for baseline characteristics, biomarkers, and treatment regimens, suggesting that factors beyond these variables might contribute to the observed disparity (hazard ratio, 1.23, 95% CI, 1.01-1.50; P=.04). Although a trend toward shorter OS was observed in Black patients treated with first-line CDK4/6 inhibitors, this difference did not reach statistical significance (hazard ratio, 1.24, 95% CI, 0.94-1.64; P=.13).

The study concluded that in the US cohort, Black patients with HR-positive/HER2-negative mBC who underwent NGS testing were more likely to receive first-line chemotherapy, less likely to have PIK3CA mutations, and less likely to receive first-line CDK4/6 inhibitors compared with White patients. This pattern was associated with a significant disparity in OS, underscoring the presence of unmet medical needs within the Black patient population. The authors emphasized the need for further research to elucidate and address the factors contributing to these racial disparities in patients with HR-positive/HER2-negative mBC.

Source

Farrokhi P, et al. Racial differences in the prevalence of biomarker alterations, treatment patterns, and clinical outcomes in hormone receptor–positive, human epidermal growth factor receptor 2–negative metastatic breast cancer: a national cohort study. Presented at: San Antonio Breast Cancer Symposium. December 10, 2024; San Antonio, TX. Abstract SESS-1375.