Liquid Biopsies, Novel Approaches and Future Directions

Abstract

Cancer is among the leading causes of death worldwide. Early diagnosis and prognosis are vital to improve patients' outcomes. The gold standard of tumor characterization leading to tumor diagnosis and prognosis is tissue biopsy. Amongst the constraints of tissue biopsy collection is the sampling frequency and the incomplete representation of the entire tumor bulk. Liquid biopsy approaches, including the analysis of circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), circulating miRNAs, and tumor-derived extracellular vesicles (EVs), as well as certain protein signatures that are released in the circulation from primary tumors and their metastatic sites, present a promising and more potent candidate for patient diagnosis and follow up monitoring. The minimally invasive nature of liquid biopsies, allowing frequent collection, can be used in the monitoring of therapy response in real time, allowing the development of novel approaches in the therapeutic management of cancer patients. In this review we will describe recent advances in the field of liquid biopsy markers focusing on their advantages and disadvantages.

Keywords: CTCs; cancer; clinical applications; ctDNA; diagnosis; exosomes; miRNA; prognosis; proteome.

Figure 1

Components of tumor circulome examined in liquid biopsies and their applications. The several analytes extracted from blood provide a wide variety of information regarding tumors. As previously stated, all analytes share different advantages and disadvantages that favor or oppose their usage in clinical settings, in tumor diagnosis, monitoring and therapy [23].