Bridging the gap: ctDNA, genomics, and equity in breast cancer care.

Circulating tumor DNA (ctDNA) has emerged as a powerful tool in precision oncology, offering a noninvasive approach to tumor profiling, minimal residual disease (MRD), and treatment monitoring. In breast cancer, ctDNA has shown promise in both metastatic and early-stage settings. However, its application and benefits have not been equitably realized across all populations. In this review, we examined the current evidence on ctDNA detection, assay performance, and clinical utility specifically within racially, ethnically, and geographically underrepresented populations. We synthesized data from genomic studies, ctDNA-based trials, and implementation research to identify disparities in ctDNA levels, mutational profiles, testing utilization, and access to genotype-matched therapies. These disparities were further compounded by structural barriers such as insurance coverage, geographic access, and limited inclusion in clinical research. Global data from low- and middle-income countries reinforced both the feasibility and the challenges of ctDNA implementation in resource-constrained settings. While ctDNA holds considerable potential to personalize breast cancer care, our findings underscore the urgent need to integrate equity into its validation, clinical application, and policy development to avoid perpetuating existing disparities.