Scientists have developed a blood test they believe can help predict the prognosis of a deadly form of brain tumour.
The test, called liquid biopsy, measures the amount of DNA shed by cancer cells in the bloodstream – known as cell-free DNA (cfDNA).
Researchers from the University of Pennsylvania in the US say this test could tell how patients will progress after they are diagnosed with Glioblastoma multiforme (GBM) – a grade 4 brain tumour.
The team believe their findings, published in the journal Clinical Cancer Research, are the first to show that higher concentrations of cfDNA in the bloodstream is linked to lower survival rates.
Dr Erica L Carpenter, a research assistant professor of medicine at the University of Pennsylvania and senior study author, said: “Doctors have begun using liquid biopsies more frequently to monitor certain cancers – particularly lung cancer – in recent years as research has shown their effectiveness in other disease sites.
“But until now, there has been little focus on the clinical utility of liquid biopsy in brain tumours.”
GBM is the most common type of malignant brain tumour, with around 2,200 cases diagnosed each year in England.
According to Public Health England, 55% of malignant brain tumours are GBMs.
The disease is known to have a poor prognosis, with 50% of patients not surviving beyond six months.
According to the scientists, GBM is difficult to treat because the tumours themselves are heterogeneous – ie, different parts of the tumour contain different genetic mutations.
This means treatments targeting one type of mutation are ineffective or only partially effective, the researchers said.
The team looked at 42 patients who were recently diagnosed with GBM.
Blood tests were taken at diagnosis, before surgery, and at regular intervals throughout their care which included chemotherapy and radiation.
The 28 patients who had a lower concentration of cfDNA before surgery had almost double the progression-free survival compared with the 14 patients with higher concentrations, the team said.
But they add their work is “more hypothesis-generating than practice-changing” at this point, and are planning to perform a larger analysis in the future.
Stephen J Bagley, an assistant professor at University of Pennsylvania’s Perelman School of Medicine, said: “If our findings are validated by further studies, it would mean that these patients may be able to get a simple blood test that would give us a more accurate assessment than imaging of whether their disease has progressed or not, as well as more data on the mutations in their tumours.”