Overview of liquid biopsy

New studies are mainly focused on the new, minimally invasive biomarkers presenting in body fluids as the real-time representative of tumors, entitled “liquid biopsy.” Liquid biopsy contains tumor-derived cells, nucleic acids (DNA, RNA), and tumor vesicles that represent the tumor characteristics. Tumor-derived cells and cells’ contents are subject to complete molecular analysis-mostly unbroken circulating tumor cells (CTCs) and cell-free circulating tumor DNA (cfDNA or ctDNA). Liquid biopsy analysis means the counting and characterization of CTCs, ctDNA/ctRNA, and exosomes to reach the main genetic information of the tumor. Advanced molecular techniques, like next-generation sequencing, droplet digital PCR, cell search, and microfluidic systems, make a comprehensive case for liquid biopsy analyses in a broad range of settings. Initially, the liquid biopsy data was just for the cancer diagnosis, preferably including screenings, but now it is considered for the prediction of response or resistance to the specific medication strategy and personalized medicine. Importantly, the detection of mutations is enabled, which has a high critical impact on making the best therapeutic decisions. The optimized practical setting of liquid biopsy in cancer has not been realized yet, but constant research is focused on establishing innovative liquid biopsy in oncology. In this chapter, we represent liquid biopsy components and summarize the principal techniques and applications of liquid biopsy in urogenital cancer.