A blood test that can detect more than 50 types of cancer before any signs of the disease is accurate enough to be rolled out as a multi-cancer screening test, scientists have said.
It is able to identify many types of cancer that are difficult to diagnose early, such as head and neck, ovarian, pancreatic, oesophageal and some blood cancers.
Scientists say the test accurately detects cancer, often before any signs or symptoms, and has a very low false positive rate.
The test is being piloted by NHS England and is aimed at people at higher risk of cancer, including the over-50s.
Dr Eric Klein, chair of the Glickman Urological and Kidney Institute, Cleveland Clinic in the US and first author on the findings published in the journal Annals of Oncology, said: “Finding cancer early, when treatment is more likely to be successful, is one of the most significant opportunities we have to reduce the burden of cancer.
“These data suggest that, if used alongside existing screening tests, the multi-cancer detection test could have a profound impact on how cancer is detected and, ultimately, on public health.”
The test, developed by US-based company Grail, looks for chemical changes in fragments of genetic code – cell-free DNA (cfDNA) – that leak from tumours into the bloodstream.
Researchers performed the test on 3,537 people – 2,823 people with cancer and 1,254 people without.
It correctly identified when cancer was present in 51.5% of cases, across all stages of the disease, and wrongly detected cancer in 0.5% of cases.
In solid tumours that do not have any screening options – such as oesophageal, liver and pancreatic cancers – the overall sensitivity (ability to generate a positive result) was twice as that for solid tumours that do have screening options, such as breast, bowel, cervical and prostate cancers.
Meanwhile, the overall sensitivity in cancers of the blood, such as lymphoma and myeloma, was 55.1%.
The test also correctly identified the tissue in which the cancer was located in the body in 88.7% of cases.
Dr Klein said: “We believe that cancers that shed more cfDNA into the bloodstream are detected more easily.
“These cancers are also more likely to be lethal, and prior research shows that this multi-cancer early detection test more strongly detects these cancer types.
“Cancers such as prostate shed less DNA than other tumours, which is why existing screening tests are still important for these cancers.”
The results of the NHS Grail pilot, which is due to start in autumn 2021, are expected by 2023. It will include 140,000 participants.
Professor Peter Johnson, national NHS clinical director for cancer, said: “This latest study provides further evidence that blood tests like this could help the NHS meet its ambitious target of finding three-quarters of cancers at an early stage, when they have the highest chance of cure.
“The data is encouraging and we are working with Grail on studies to see how this test will perform in clinics across the NHS, which will be starting very soon.”