A blood test that can detect more than 50 different types of cancer has shown promise in a trial involving thousands of NHS patients, scientists have said. The Galleri test, which is currently available in the US, is also able to pinpoint where in the body the disease is coming from with 85% accuracy.
In the Symplify trial, the test was able to detect signs of cancer in 323 out of the 6,238 people who had visited their GP with suspected symptoms, in England or Wales. Of those 323 patients, 244 were subsequently diagnosed with cancer, giving a positive predictive accuracy of 75%, the researchers said.
Around 2% of patients with a negative result were found to have cancer. Overall, the test correctly revealed cancer 66% of the time.
The accuracy of the test was also dependent on the stage of the cancer – ranging from 24% for very early-stage (stage I) tumours to 95% for advanced disease (stage IV). The most common cancer diagnoses were bowel (37%), lung (22%), uterine (8%), oesophago-gastric (6%) and ovarian (4%).
Catching cancer early is vital for people to receive prompt treatment and potentially save thousands of lives in the UK every year.
Brian Nicholson, associate professor at the Nuffield Department of Primary Care Health Sciences, University of Oxford, said the findings suggest that multi-cancer early detection tests (MCEDs) can play a role “to confirm that symptomatic patients should be evaluated for cancer before pursuing other diagnoses”.
He said: “Most patients diagnosed with cancer first see a primary care physician for the investigation of symptoms suggestive of cancer, like weight loss, anaemia, or abdominal pain, which can be complex as there are multiple potential causes. New tools that can both expedite cancer diagnosis and potentially avoid invasive and costly investigations are needed to more accurately triage patients who present with non-specific cancer symptoms."
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Professor Helen McShane, director of the NIHR Oxford Biomedical Research Centre, said: “We are committed to diagnosing cancers earlier, when they can be cured, and this study is an important step on that journey.”
How does the Galleri test work?
The Galleri test works by looking for chemical changes in fragments of genetic code – cell-free DNA (cfDNA) – that leak from tumours into the bloodstream. Some cancer tumours are known to shed DNA into the blood a long time before a person would start experiencing symptoms.
The test does not detect all cancers and does not replace NHS screening programmes, such as those for breast, cervical and bowel cancer. In the US, it has been recommended for people at higher risk of cancer, including the over-50s.
Developed by Californian company Grail, the test is also being trialled in the NHS to see if it can detect hidden cancers in people without symptoms, with results expected later this year. The findings from the Symplify trial were presented at the American Society of Clinical Oncology conference, in Chicago, and published in The Lancet Oncology journal.
