Liquid Biopsy in Precision Oncology: Expanding Clinical Applications for Molecular Characterization, Disease Monitoring, and Personalized Management of Solid Tumors
Liquid biopsy has rapidly emerged as one of the most promising innovations in precision oncology by providing minimally invasive access to tumor-derived biomarkers throughout the clinical course of cancer. This review analyzes the current evidence regarding the clinical applications of liquid biopsy beyond early cancer detection, emphasizing its role in molecular profiling, therapeutic selection, treatment monitoring, minimal residual disease assessment, identification of resistance mechanisms, and evaluation of tumor heterogeneity in patients with solid tumors. A comprehensive literature review was conducted using major biomedical databases, selecting high-quality publications focused on circulating tumor DNA, circulating tumor cells, extracellular vesicles, circulating RNA, and other emerging biomarkers. The available evidence demonstrates that circulating tumor DNA currently represents the most clinically validated biomarker because of its high analytical performance and increasing incorporation into precision oncology protocols. Liquid biopsy has shown particular utility in lung, colorectal, breast, and prostate cancers, where molecular information directly contributes to personalized treatment decisions. Nevertheless, several barriers continue to limit universal implementation, including high costs, limited molecular infrastructure, methodological variability, and unequal access to advanced genomic technologies, particularly in developing countries. Ongoing technological improvements, international collaboration, and methodological standardization are expected to further expand the clinical applications of liquid biopsy and facilitate its incorporation into routine oncology practice. Overall, liquid biopsy represents a transformative strategy that complements conventional tissue biopsy and supports more personalized, dynamic, and evidence-based management of solid tumors.