Role of liquid biopsy in genitourinary (GU) cancers

Liquid biopsy is a noninvasive diagnostic and monitoring method that provides molecular information about disease by analyzing tumor-derived biomaterials obtained from body fluids-primarily blood, as well as plasma, urine, saliva, and others-including circulating tumor DNA (ctDNA), RNA, circulating tumor cells, and exosomes. Consequently, liquid biopsy has become one of the most intensely investigated and rapidly evolving fields in contemporary oncology.

This narrative review covers the molecular components and isolation techniques underlying liquid biopsy platforms, and examines their clinical applications across prostate cancer, bladder cancer, renal cell carcinoma, and testicular germ cell tumors, encompassing pre-biopsy risk stratification, treatment-response monitoring, detection of resistance mechanisms, and minimal residual disease surveillance.

Clinical utility is now the main barrier to routine adoption of liquid biopsy in genitourinary cancers. Prospective studies must demonstrate that liquid biopsy-guided strategies, including biopsy avoidance, perioperative MRD driven escalation or de-escalation, and adaptation of therapy in the metastatic setting, improve clinically meaningful outcomes and are cost-effective. Standardized pre-analytical procedures, harmonized reporting thresholds, and clear management algorithms for discordant results will be essential for reliable real world implementation.