This special issue is dedicated to the incorporation of liquid biopsy in clinical decision making for solid tumors. Liquid biopsy is a non-invasive tool that could overcome tissue genotyping limits, providing a more complete molecular profiling that could catch the complex molecular pattern of heterogeneous tumors along the course of tumor disease. Remarkably, the role of circulating tumor DNA analysis has been well established in metastatic setting, in which could potentially guide treatment decision, monitor response and early catch treatment resistance. Moreover, very interesting data come from the use of ctDNA in the early stage of tumors, for the early detection and the detection of minimal residual disease (MRD), which reflects the presence of tumor cells left after surgery or local treatment or disseminated from the primary tumor in patients with no sign of clinical or radiological progression.

The aim of this special issue is to collect original translational research data and updated reviews on the use of liquid biopsy in oncology, to provide optimal patient selection for chemotherapy, targeted agents and immunotherapy and explore the role of ctDNA as a potential prognostic and predictive biomarker in oncologic diseases.

Keywords: Precision medicine, liquid biopsy, circulating tumor DNA, biomarker, treatment resistance, minimal residual disease