Scientists from Cancer Research UK in Cambridge have advanced research into liquid biopsies for brain tumours by detecting tumour DNA in the fluid around the spine and brain.

Liquid biopsies are samples of fluids collected from patients to monitor disease, an easier alternative to tumour biopsies. This could be hugely helpful where ordinary biopsies are too difficult or risky.

The study, published in EMBO Molecular Medicine, looked at cerebrospinal fluid (CSF) in 13 patients with a glioma tumour using shallow whole-genome sequencing, which looks for large genetic changes in the DNA.

Tumour DNA was detected in five of the patients by looking at DNA fragments, which are shorter than those from healthy cells. In one patient, several tumour tissue samples were compared to the patient’s CSF. The genetic changes largely matched, but the CSF contained changes missing in some of the tumour tissue samples. This could mean CSF samples reflect genetic alterations found in brain tumours.

Cancer Research UK’s Chief Clinician Professor Charles Swanton said that there was an urgent need for this type of research to increase brain tumour survival rates: “This study lays important groundwork that brings the possibility of liquid biopsies for this hard to treat disease one step closer.

“The researchers will now need to expand this work into larger numbers of patients and find out whether this approach could have applications in the clinic, such as indicating whether a patient’s treatment is working.”