The detection of tumour-derived DNA in cerebrospinal fluid (CSF) could be used to track tumour progression in some gliomas, reports a study in Nature this week. Gliomas are the most common cancerous brain tumours in adults. This liquid biopsy approach could be a minimally invasive alternative to sampling brain tissue for disease classification, and could help to guide the treatment of patients with gliomas.
Monitoring glioma progression can require repeated biopsies because the glioma genome evolves during the course of the disease. Taking liquid biopsies (rather than surgically removing brain tumour tissue) is an attractive method for analysing tumour DNA, although detection of this genetic information in blood samples has been challenging. Ingo Mellinghoff and colleagues demonstrate that the CSF might provide a more comprehensive source of tumour-derived DNA in patients with gliomas.
The authors sampled the CSF, collected by lumbar puncture, of 85 patients with gliomas. Tumour-derived DNA was detected in nearly half (42) of the patients, and was associated with tumour size, progression, and disease outcome. The risk of death was four times higher in patients with circulating tumour DNA in their CSF than in those without. The genetic material found in the CSF offers an accurate representation of the tumour genome, the authors note. They add that not all gliomas seem to shed DNA into the CSF, but suggest that the presence of tumour-derived DNA may provide an early indicator of brain tumour progression.