Liquid Biomarkers for Improved Diagnosis and Classification of CNS Tumors

Abstract

Liquid biopsy, as a non-invasive technique for cancer diagnosis, has emerged as a major step forward in conquering tumors. Current practice in diagnosis of central nervous system (CNS) tumors involves invasive acquisition of tumor biopsy upon detection of tumor on neuroimaging. Liquid biopsy enables non-invasive, rapid, precise and, in particular, real-time cancer detection, prognosis and treatment monitoring, especially for CNS tumors. This approach can also uncover the heterogeneity of these tumors and will likely replace tissue biopsy in the future. Key components of liquid biopsy mainly include circulating tumor cells (CTC), circulating tumor nucleic acids (ctDNA, miRNA) and exosomes and samples can be obtained from the cerebrospinal fluid, plasma and serum of patients with CNS malignancies. This review covers current progress in application of liquid biopsies for diagnosis and monitoring of CNS malignancies.

Keywords: CSF; CTC; EV; ctDNA; exosome; liquid biopsy; microRNA; plasma; proteomics.

Figure 1

Liquid biopsy approaches utilized in central nervous sytem tumor diagnosis or monitoring. Upper left panel: CNS tumor of unknown diagnosis with local brain inflammation. Middle panel: Tumor analyte enters biofluid, with circulating tumor cell entering bloodstream and a representative example process is shown. Lower right panel: analytes of interest depicted in the bloodstream as representative biofluid, including circulating tumor cells, circulating tumor DNA (ctDNA), microRNAs (miRNA), proteins, metabolites and exosomes/extracellular vesicles (EVs) (created with BioRender.com, accessed on 14 February 2021).