Liquid Biopsy: A New, Non-Invasive Early Diagnostic and Prognostic Tool in Oncology

Abstract

Cancer is essentially a genetic disease. Neoplastic progression consists of a subsequent series of genetic alterations that cumulate. In the bloodstream of an affected subject, circulating tumor cells (CTC) and/or small deoxy-ribonucleic acid (DNA) fragments, known as circulating tumor DNA (ctDNA), can be found as a consequence of cancer cells death. Cell-free circulating DNA (cfDNA) consists of small fragments of DNA that are found free in plasma or serum, but also in other body fluids. The term liquid biopsy (LB) describes a highly sensitive method (based on a simple sampling of peripheral blood) for the isolation and analysis of cfDNA, which can also contain ctDNA and CTC. Its purpose is to look for cancer cells or portions of their DNA that are circulating in the blood. LB can be used to help find cancer in an early stage. It also has the additional advantage of being largely non-invasive and, therefore, being done more frequently, allowing better tumor and genetic mutations tracking. It can also be used to validate the efficacy of a drug for cancer treatment by taking multiple samples of LB within a few weeks. This technology can also be beneficial for patients after treatment to control relapse. The aim of this work is to give an overview of this technique, from its history, state-of-the-art, and methodology of execution, to its applications in oncology and with a hint to the gynecological field.