Liquid biopsy for improving diagnosis and monitoring of CNS lymphomas: A RANO review

Background. The utility of liquid biopsies is well documented in several extracranial and intracranial (brain/leptomeningeal metastases, gliomas) tumors. Methods. The RANO (Response Assessment in Neuro-Oncology) group has set up a multidisciplinaryTask Force to critically review the role of blood and cerebrospinal fluid (CSF)–liquid biopsy in CNS lymphomas, with a main focus on primary central nervous system lymphomas (PCNSL). Results. Several clinical applications are suggested: diagnosis of PCNSL in critical settings (elderly or frail patients, deep locations, and steroid responsiveness), definition of minimal residual disease, early indication of tumor response or relapse following treatments, and prediction of outcome. Conclusions. Thus far, no clinically validated circulating biomarkers for managing both primary and secondary CNS lymphomas exist.There is need of standardization of biofluid collection, choice of analytes, and type of technique to perform the molecular analysis.The various assays should be evaluated through well-organized central testing within clinical trials.