Figure 1.

The liquid biopsy workflow. In oncology, a liquid biopsy is a minimally invasive alternative to surgical tumour sampling, involving the collection and analysis of a peripheral blood sample. Blood plasma/serum is a source of several circulating analytes with potential clinical utility, namely cell-free DNA, cell-free RNA (mRNA and microRNA), extracellular vesicles (exosomes and microvesicles), tumour-educated platelets (TEPs) and tumour cells. Cell-free nucleic acids are a potential source of tumour-specific genomic alterations such as gene mutations, translocations, copy number alterations (CNAs), DNA methylation and gene expression changes. TEPs are a source of nucleic acids, and extracellular vesicles and tumour cells are a source of nucleic acids and protein. Molecular analysis of circulating biomarkers can impact the clinical management of cancer patients by enabling personalized medicine, monitoring of therapeutic response and assessment of disease prognosis/risk.