ObjectiveTo assess the clinical value of liquid biopsy in breast cancer care, with a focus on its potential to complement tissue biopsy in diagnosis, treatment monitoring, and disease management. MethodA narrative review of recent literature was performed, examining the biological basis and clinical relevance of key liquid biopsy markers, including circulating tumor DNA (ctDNA), circulating tumor cells, and extracellular vesicles, in the context of breast cancer. ResultsAmong the markers reviewed, ctDNA can non-invasively detect mutations in key genes, such as ESR1, PIK3CA, HER2, and BRCA1/2, with results that are largely consistent with those from tissue samples. In addition to mutation testing, ctDNA can be measured repeatedly over time, making it useful for early screening, monitoring of high-risk individuals, efficacy evaluation, evolution of drug-resistant clones, and monitoring of minimal residual disease. Circulating tumor cells count and phenotypic analysis provide prognostic information regarding recurrence risk and survival, and single cell analysis helps reveal tumor spatiotemporal heterogeneity. Extracellular vesicles carry nucleic acids and proteins of tumor origin and have shown potential value in early diagnosis and disease monitoring. Liquid biopsy has shown clinical value in the diagnosis of advanced breast cancer, including cases with central nervous system involvement. However, current limitations in detection sensitivity and specificity, combined with the lack of standardized testing procedures, continue to restrict its clinical use. As a result, tissue biopsy remains the gold standard for initial pathological diagnosis and molecular classification. ConclusionsLiquid biopsy and tissue biopsy have different but complementary roles in breast cancer care. Tissue biopsy remains the basis for diagnosis and molecular subtyping, while liquid biopsy is more suitable for continuous monitoring and molecular stratified guidance over the course of disease. With advances in detection methods, combined use of multiple markers, improved standardization, and the integration of artificial intelligence for multi-omics data analysis, liquid biopsy holds promise for advancing more personalized and dynamic management for breast cancer patients.
