Liquid Biopsies: Flowing Biomarkers.

Metastatic dissemination accounts for most of the death in patients during cancer progression. There is thus an urge to identify specific biomarkers as proxies for cancer progression and assessment of treatment efficiency. Cancer is a systemic disease involving the shuttling of tumor cells and tumor secreted factors to distant organs, mostly via biofluids. During this transfer, these factors are accessible for easy sampling and therefore constitute a unique source of information witnessing the presence and the evolution of the disease. Hence, liquid biopsies offer multiple advantages, including simple and low-invasive sampling procedures, low cost, and higher compliance. Importantly, liquid biopsies are adapted to personalized medicine allowing a longitudinal follow-up to monitor treatment efficiency or resistance, and risk of relapse.The evolution of methodologies to isolate circulating tumor cells (CTCs) and extracellular vesicles (EVs) from blood samples associated with the characterization of their membrane surface repertoire and content have been instrumental in the emergence of liquid biopsies as an easy and non-invasive alternative as opposed to classical surgery-mediated tumor biopsies.In this chapter, we comment on CTCs and EVs carrying features with great potential as cancer biomarkers. More specifically, we focus on the adhesive and mechanical properties of CTCs as metastatic markers. We also consider the recent development of EVs isolation methods and the identification of new biomarkers. Finally, we discuss their relevance as cancer prognosis tools.