Malignant gliomas are the most common and lethal primary intracranial tumors. To 
date, no reliable biomarkers for the detection and risk stratification of 
gliomas have been identified. Recently, we demonstrated significant levels of 
microRNAs (miRNAs) to be present in cerebrospinal fluid (CSF) samples from 
patients with primary CNS lymphoma. Because of the involvement of miRNA in 
carcinogenesis, miRNAs in CSF may serve as unique biomarkers for minimally 
invasive diagnosis of glioma. The objective of this pilot study was to identify 
differentially expressed microRNAs in CSF samples from patients with glioma as 
potential novel glioma biomarkers. With use of a candidate approach of miRNA 
quantification by reverse-transcriptase polymerase chain reaction (qRT-PCR), 
miRNAs with significant levels in CSF samples from patients with gliomas were 
identified. MiR-15b and miR-21 were differentially expressed in CSF samples from 
patients with gliomas, compared to control subjects with various neurologic 
disorders, including patients with primary CNS lymphoma and carcinomatous brain 
metastases. Receiver-operating characteristic analysis of miR-15b level revealed 
an area under the curve of 0.96 in discriminating patients with glioma from 
patients without glioma. Moreover, inclusion of miR-15b and miR-21 in combined 
expression analyses resulted in an increased diagnostic accuracy with 90% 
sensitivity and 100% specificity to distinguish patients with glioma from 
control subjects and patients with primary CNS lymphoma. In conclusion, the 
results of this pilot study demonstrate that miR-15b and miR-21 are markers for 
gliomas, which can be assessed in the CSF by means of qRT-PCR. Accordingly, 
miRNAs in the CSF have the potential to serve as novel biomarkers for the 
detection of gliomas.