For many cancers, doctors are increasingly concerned about the DNA released into the blood by solid tumors to help diagnose and monitor them.But brain cancer is different because of the natural blockage of the blood-brain barrier.

However, researchers at the Rogers Cancer Center at the University of Michigan and CS Mott Children's Hospital at the Michigan Medical School are optimistic that CSF could be a valuable source of tumor DNA that could help monitor and treat gliomas in pediatric cancer patients with aggressive brain tumors.

Not only do mutations in these tumors change over time, leading to changes in potential treatment paths, but the amount of tumor DNA in a patient's spinal fluid can also help doctors know whether the changes seen in a patient's imaging scan are a true sign of tumor progression or simply a response to cancer treatment.

"We know from past studies that the genetic sequences of these tumors, including information about the mutations that drive them, can be found in the spinal fluid, but they are not yet included in the collection process," carr said.Koschmann, M.D., a Mott pediatric oncologist and researcher at the Carr Pediatric Brain Tumor Center in Chad, Mich."That's something we've always wanted to change."

A new study by Koschmann and a team of researchers from UM suggests that new portable DNA sequencing technology could make this "liquid biopsy" approach feasible.The team's findings, published in clinical Cancer Research, a journal of the American Association for Cancer Research, are the first to use nanopore gene sequencing technology for this purpose.

"We're using modern handheld DNA sequencing equipment in a way that's never been done before," said Lead author Amy Bruzek, a neurosurgeon at the University of Michigan Medical School."This allows us to use portable instruments to bring it into the operating room and quickly analyze the TUMOR DNA in the patient's cerebrospinal fluid."

Nanopores work by measuring changes in the electrical current of biomolecules as they pass through holes in the collecting surface.Different values correspond to different letters in the genetic code, so DNA sequences can be read.

The study used equipment made by Oxford Nanopore Technology, a spin-off from Oxford University, to look for clinically viable alternatives in samples from 12 patients with high-grade glioma.The device costs about $1,000, weighs a pound and can be connected to a laptop, giving it an advantage over leading laboratory models, which typically cost tens of thousands of dollars, require dedicated space and are more complex to operate, the researchers noted.It also requires much less spinal fluid than other sequencing methods.

In nearly 130 samples, the researchers found that the new method worked well and that the results could be confirmed using accepted sequencing methods.

"This study shows an opportunity to effectively monitor the efficacy of drugs in clinical trials in children with glioma by collecting spinal fluid at different time points," Bruzek said.

At present, in the initial operation, the glioma is removed as much as possible, and doctors then look at an image scan to track changes in the tumor.