**1.2. Liquid biopsy**

The utilisation of liquid biopsies continues to generate significant attention as it represents a platform that has the potential to provide rapidly evaluable and non-invasive, genomic characterisation of a patient's cancer. In simple terms, liquid biopsy refers to analyses that utilise blood or bodily fluids that contain circulating tumour cells (CTC) and/or fragments of nucleic acids or proteins that are derived from primary and/or secondary tumour sites. This material can then be interrogated to provide comprehensive information about the tumour genome and other biological characteristics of the disease. Moreover, liquid biopsies can be used to monitor the effects of therapy and may provide early evidence of recurrence or relapse of disease enabling early and informed changes in disease treatment. In this section, the two most widely studied types of liquid biopsy sources, CTC and cell-free nucleic acids (CFNA), will be discussed.
