The "Liquid Biopsy": the Role of Circulating DNA and RNA in Central Nervous System Tumors

The detection of tumor-derived circulating nucleic acids in patients with cancer, known as the "liquid biopsy," has expanded from use in plasma to other bodily fluids in an increasing number of malignancies. Circulating nucleic acids could be of particular use in central nervous system tumors as biopsy carries a 5-7% risk of major morbidity. This application presents unique challenges that have limited the use of cell-free DNA and RNA in the diagnosis and monitoring of CNS tumors. Recent work suggests that cerebrospinal fluid may be a useful source of CNS tumor-derived circulating nucleic acids. In this review, we discuss the available data and future outlook on the use of the liquid biopsy for CNS tumors.