The Galleri 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, the study showed.
Of those 323 patients, 244 were subsequently diagnosed with cancer, giving a positive predictive accuracy of 75 per cent, the researchers said.
The findings could mean the blood test has the potential to spot and rule out cancer in people with symptoms, speeding up diagnosis.
In 85 per cent of those positive cases, the test was able to pinpoint the original site of the cancer.
The test, which is being trialled by researchers at the University of Oxford, detects fragments of tumour DNA in 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 predicted 37 per cent of bowel cancer cases, 22 per cent of lung cancer cases, and 8 per cent of uterine cancer cases, as well as 6 per cent of oesophago-gastric cases, and 4 per cent of ovarian cancer cases.
However, the accuracy of the test varied depending on the stage of the cancer. The Galleri test was able to accurately predict 95 per cent of advanced-stage tumours, while it was only able to predict 24 per cent of very early-stage cancers.
The test does not detect all cancers and does not replace NHS screening programmes, such as those for breast, cervical and bowel cancer.
Researchers said the test is a “work in progress”, but the NHS trial is showing “real promise”.
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.
NHS national director for cancer Prof Peter Johnson said: “This study is the first step in testing a new way to identify cancer as quickly as possible, being pioneered by the NHS – earlier detection of cancer is vital and this test could help us to catch more cancers at an earlier stage and help save thousands of lives.”
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 added: “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.”
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.”
The findings from the trial were presented at the American Society of Clinical Oncology conference, in Chicago, and published in The Lancet Oncology journal.