Advances on Liquid Biopsy Analysis for Glioma Diagnosis

Abstract

Gliomas comprise the most frequent primary central nervous system (CNS) tumors, characterized by remarkable genetic and epigenetic heterogeneity, difficulty in monitoring, and increased relapse and mortality rates. Tissue biopsy is an established method of tumor cell collection and analysis that enables diagnosis, classification of different tumor types, and prediction of prognosis upon confirmation of tumor's location for surgical removal. However, it is an invasive and often challenging procedure that cannot be used for frequent patient screening, detection of mutations, disease monitoring, or resistance to therapy. To this end, the minimally invasive procedure of liquid biopsy has emerged, allowing effortless tumor sampling and enabling continuous monitoring. It is considered a novel preferable way to obtain faster data on potential tumor risk, personalized diagnosis, prognosis, and recurrence evaluation. The purpose of this review is to describe the advances on liquid biopsy for glioma diagnosis and management, indicating several biomarkers that can be utilized to analyze tumor characteristics, such as cell-free DNA (cfDNA), cell-free RNA (cfRNA), circulating proteins, circulating tumor cells (CTCs), and exosomes. It further addresses the benefit of combining liquid biopsy with radiogenomics to facilitate early and accurate diagnoses, enable precise prognostic assessments, and facilitate real-time disease monitoring, aiming towards more optimal treatment decisions.

Keywords: LINE-1; cfDNA; circulating tumor cells; epigenetics; exosomes; glioblastoma; glioma; liquid biopsy; radiogenomics; tissue biopsy.

Figure 1

Detection of various tumor analytes in a variety of biofluids (CSF, urine, blood) with liquid biopsy. Several types of biofluids can be collected by using liquid biopsy and tumor-derived analytes (cfDNA, cfRNA, exosomes) measured using genomic processes to aid in tumor diagnosis, prognosis, and monitoring response to therapy (created with BioRender access on 24 June 2023).

Figure 2

Impact of radiogenomics on diagnosis of brain tumors. Radiogenomics integrates large amounts of quantitative data obtained from medical images with individual genomic phenotypes from liquid biopsy analysis to enable efficient glioma diagnosis (created with BioRender, accessed 12 July 2023).