A blood test for more than 50 types of cancer has shown promise in a major NHS trial, researchers say.
The test, called Galleri, correctly detected two out of three cancers among 5,000 people who had visited their GP with suspicious symptoms in England and Wales.
In 85% of those positive cases, the test also identified the site where the cancer originated.
The Galleri test looks for distinctive changes in snippets of genetic code that are shed by different types of cancer. Early detection of treatable cancer can save lives.
The test remains largely a “work in progress”, say the Oxford University researchers who conducted the NHS trial.
But scientists believe the test could increase the number of cancers identified.
Often, patients have symptoms such as weight loss, which can have a variety of possible causes, and require screening for their illnesses requiring multiple tests and hospital visits.
More than 350 of the people who participated in the study, the largest of its kind in patients with suspicious symptoms of cancer, were later diagnosed with that disease using traditional methods such as scans and biopsies.
It was discovered that:
• 75% of patients who tested positive in the blood test had cancer
• 2.5% of those who tested negative had cancer
Although the test is not precise enough to “confirm or rule out the presence of cancer”, it is really useful for patients, the trial’s lead investigator, Mark Middleton, told the BBC.
“The test was 85% accurate in detecting where the cancer was starting. And that can be really helpful because a lot of times it’s not immediately obvious when you have a patient in front of you what tests are needed to determine if their symptoms are due to a cancer,” he added.
“With that test prediction, we can decide whether to do an endoscopic exam or a scan and make sure we do the right test the first time.”
The findings will be presented at the American Society of Clinical Oncology conference in Chicago and published in The Lancet Oncology.
The NHS has also been using the Galleri test, developed by the Californian company Grail, on thousands of people without symptoms, to determine if it can detect hidden cancers.
Initial results are expected this year and, if positive, the NHS in England plans to roll out the test to a further 1 million people in 2024 and 2025.
The test is particularly good at finding hard-to-detect cancers, such as cancers of the head and neck, bowel, lung, pancreas, and throat.
Dr David Crosby, from the non-profit organization Cancer Research UK, said: “The study findings suggest that this test could be used to help GPs make clinical assessments, but much more research is needed in a larger trial to see if it could improve medical diagnoses and ultimately patient outcomes.”
The NHS’s national cancer director, Professor Peter Johnson, said: “This study is the first step in testing a new way of identifying cancer as quickly as possible.”
Johnson added that “early detection of cancer is vital and this test could help detect more cancers at an earlier stage and help us save thousands of lives.”
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