A liquid biopsy, also known as fluid biopsy or fluid phase biopsy, is the sampling and analysis of non-solid biological tissue, primarily blood. Like traditional biopsy, this type of technique is mainly used as a diagnostic and monitoring tool for diseases such as cancer, with the added benefit of being largely non-invasive. Liquid biopsies may also be used to validate the efficiency of a cancer treatment drug by taking multiple samples in the span of a few weeks. The technology may also prove beneficial for patients after treatment to monitor relapse.

The clinical implementation of liquid biopsies is not yet widespread but is becoming standard of care in some areas. Liquid biopsy refers to the molecular analysis in biological fluids of nucleic acids, subcellular structures, especially exosomes, and, in the context of cancer, circulating tumor cells. 

In the present book, seventeen typical literatures about liquid biopsies published on international authoritative journals were selected to introduce the worldwide newest progress, which contains reviews or original researches on liquid biopsies. We hope this book can demonstrate advances in liquid biopsies as well as give references to the researchers, students and other related people.