A simple urine test could detect a deadly brain tumour that can kill within 12 months, scientists have discovered. The test carried out routinely in check-ups could spot signs of glioma in its early stages when it is most treatable.
And the inventors believe the same technique could be used to spot early signs of other hard-to-detect cancers. Most sufferers aren't aware of their brain tumour until they get symptoms such as paralysis of the limbs.
But now, researchers have found a way of capturing cancer DNA using nanowires in urine which will give patients vital extra time. Led by a team at Japan's Nagoya University, scientists were able to successfully detect IDH1 mutation, a characteristic genetic mutation of gliomas.
Brain cancers are often detected late and so are difficult to remove using surgery. Gliomas have a survival time as low as 12-18 months, so early detection is crucial. The team, whose findings are published in the journal Biosensors and Bioelectronics,
suggest their invention could be used in routine physicals to catch early signs of the disease. The test works because brain tumours release small DNA particles as they grow and although much is cleaned up by the body, excess particles are excreted in urine.
Professor Takao Yasui, a member of the research group, said: “The detection of these cells as a non-invasive way to check for cancer has been approved by the US Food and Drug Administration for cancer screening, diagnosis, prognosis, and monitoring of cancer progression and treatment response.
“However, a major bottleneck is the lack of techniques to isolate these particles, known as cfDNA efficiently from urine, as the excreted cfDNA may be short, fragmented, and low concentration.”
The team came up with a solution - a catch-and-release method on zinc oxide (ZnO) nanowire surfaces to capture cfDNA and extracellular vesicles from gliomas. ZnO was chosen because water molecules adsorb on the surface of ZnO nanowires. These water molecules then form hydrogen bonds with any cfDNA in the urine sample.
The bonded cfDNA can then be washed out, allowing researchers to isolate trace amounts of it in a sample. Prof Yasui said: "Our technique was a resounding success.
"We succeeded in isolating urinary cfDNA, which was exceptionally difficult with conventional methods. Although in a previous experiment, we showed that our nanowire could capture cancer extracellular vesicles, which we found in this sample too; the surprising thing was the capture of cfDNA using a similar technique.
"When we extracted the cfDNA, we detected the IDH1 mutation, which is a characteristic genetic mutation found in gliomas. This was exciting for us, as this is the first report of the detection of the IDH1 mutation from a urine sample as small as 0.5 ml.
“This research overcomes the shortcomings of currently used methods by using chemical, biological, medical and nanotechnological techniques to provide a state-of-the-art method for the clinical use of urinary cfDNA, especially as an analytical tool to facilitate the early diagnosis of cancer
“Although we tested gliomas, this method opens new possibilities for the detection of tumour mutations. If we know the type of mutation to look for, we can easily apply our technique to detect other types of tumours, especially the detection of those that cannot be isolated by conventional methods.”
