Advanced Technologies for Liquid Biopsy in Cancer Detection and Monitoring

Cancer is a significant global health issue. Early detection is key for improving treatment outcomes and increasing survival rates. Tissue biopsies provide useful histological and molecular information; however they are an invasive and may not accurately reflect the heterogeneous nature of tumours. Non-invasive methods are therefore being developed. Liquid biopsy allows tumour biomarkers to be analysed from bodily fluids such as blood. Circulating tumour DNA (ctDNA), circulating tumour cells (CTCs), extracellular vesicles (EVs) and cell-free RNA (cfRNA) are all biomarkers that can be found in liquid biopsies. Recent developments in technology such as polymerase chain reaction (PCR), next-generation sequencing (NGS), DNA methylation, microfluidics, biosensors, nanotechnology and artificial intelligence (AI) have increased the use of liquid biopsies. They can now be used to aid cancer profiling, monitor response to treatment, identify minimal residual disease and detect cancer recurrence. There are several challenges within liquid biopsies, including low biomarker concentrations, variability between samples, interference from clonal haematopoiesis, high costs of testing and limited clinical validation. This review outlines the main biomarkers used for liquid biopsies, new technologies emerging to detect them, their uses in the clinic, limitations with liquid biopsies and future research. Technological advancements and large clinical validation will be key in making liquid biopsies a reliable tool for personalising cancer management.