Cerebrospinal fluid biomarkers of malignancies located in the central nervous system

CNS malignancies include primary tumors that originate within the CNS as well as secondary tumors that develop as a result of metastatic cancer. The delicate nature of the nervous systems makes tumors located in the CNS notoriously difficult to reach, which poses several problems during diagnosis and treatment. CSF can be acquired relatively easy through lumbar puncture and offers an important compartment for analysis of cells and molecules that carry information about the malignant process. Such techniques have opened up a new field of research focused on the identification of specific biomarkers for several types of CNS malignancies, which may help in diagnosis and monitoring of tumor progression or treatment response. Biomarkers are sought in DNA, (micro)RNA, proteins, exosomes and circulating tumor cells in the CSF. Techniques are rapidly progressing to assess these markers with increasing sensitivity and specificity, and correlations with clinical parameters are being investigated. It is expected that these efforts will, in the near future, yield clinically relevant markers that aid in diagnosis, monitoring and (tailored) treatment of patients bearing CNS tumors. This chapter provides a summary of the current state of affairs of the field of biomarkers of different types of CNS tumors.