In a retrospective cohort study reported in JAMA Network Open, Podany et al identified differences in circulating tumor DNA (ctDNA) profiles, targeted therapy use, and survival outcomes in Black vs White patients with metastatic breast cancer.
Study Details
The U.S. multicenter study involved 1,327 women, including 140 Black and 1,057 White patients who underwent genomic profiling between January 2015 and December 2023.
Key Findings
ctDNA profiling showed that Black patients had significantly higher rates of GATA3 single-nucleotide variants (SNVs; odds ratio [OR] = 2.31, 95% CI = 1.17–4.54, P = .02) and CCND2 copy number variants (OR = 4.63, 95% CI = 1.79–11.97, P = .002) vs White patients on multivariate analysis.
Among patients with PIK3CA SNVs, receipt of targeted PI3K inhibitors was less common (P = .04) among Black patients (1 of 17, 5.9%) vs White patients (45 of 156, 28.8%). No significant differences between groups were observed in the use of CDK4/6 and mTOR inhibitors, agents that do not require a targetable alteration.
From the time of ctDNA testing, overall survival among Black patients (median = 22.0 months, interquartile range [IQR] = 8.1–52.0 months) was significantly shorter (P = 5.58 x 10-22) vs White patients (median = 29.0, IQR = 11.2–61.0 months). Overall, patients with higher variant allele frequency (VAF) had shorter overall survival than did those with lower VAF; the shortest median overall survival was observed in Black patients with VAFs ≥ 3.3%.
The investigators concluded: “This cohort study of patients with [metastatic breast cancer] found somatic differences, shorter overall survival, and targeted treatment disparities in PI3K inhibitor use in Black compared with White patients despite equal incidence of PIK3CA alterations. Researchers should consider these differences when designing future research and interventions to address the striking and persistent outcomes gap between Black and White patients with [metastatic breast cancer].”
Andrew A. Davis, MD, of Washington University in St Louis, is the corresponding author of the JAMA Network Open article.
Disclosure: For full disclosures of the study authors, visit jamanetwork.com.
