Liquid biopsy in the diagnosis of primary brain tumors

The diagnosis of primary brain tumors at presentation and with progression presents unique challenges, in part due to the inherent risks and limitations of neurosurgical sampling. Emerging liquid biopsy techniques analyzing circulating tumor DNA (ctDNA) in the cerebrospinal fluid (CSF) are potentially revolutionary, affording a minimally invasive means of collecting valuable tumor-related information. Here we review the most salient factors contributing to successful detection of CSF ctDNA, the most developed ctDNA assay techniques and the clinical contexts in which CSF liquid biopsy has been applied. Future opportunities for liquid biopsy advancement are also explored. Integration of these techniques into routine clinical care will require rigorous validation through clinical trials and standardization of assay pipelines but holds great promise for the future of neuro-oncology.