December 04, 2020
A simple blood test, claimed to detect more than 50 types of cancer, will be used in a pilot trial by National Health Service (NHS) England in a bid to increase rates of early-stage diagnosis, in particular for cancers that are currently difficult to diagnose.
"Early detection, particularly for hard-to-treat conditions like ovarian and pancreatic cancer, has the potential to save many lives," said NHS Chief Executive Sir Simon Stevens in a statement.
The pilot trial will use the Galleri blood test, developed by Grail. Stevens described the blood test as "promising" and said it could "be a game-changer in cancer care, helping thousands more people to get successful treatment."
However, some clinicians have expressed concerns over the potential for false positive results with the test.
Results of a study of the Galleri blood test, published earlier this year, showed that the test detected 50 types of cancer with a specificity of 99.3% and a false positive rate of 0.7%.
It also correctly identified the originating tissue in 90% of cases. However, the sensitivity was lower, at 67%, for the 12 most common cancers, as reported at the time by Medscape Medical News.
The senior author of that study, Michael Seiden, MD, PhD, president of the US Oncology Network, The Woodlands, Texas, noted that it was not a screening study: the test had been used in patients with cancer and in healthy volunteers. He said the test "is intended to be complementary to, and not replace, existing guideline-recommended screening tests and might provide new avenues of investigation for cancers that don't currently have screening tests."
The Galleri test uses next-generation sequencing to analyze the arrangement of methyl groups on circulating cell-free DNA in a blood sample.
Several other blood tests for cancer are under development, including the CancerSEEK test, which has been reported to be able to identify eight common cancers. It measures circulating tumor DNA from 16 genes and eight protein biomarkers and then uses machine learning to analyze the data.
Improving Early Detection Rates
The pilot trial of the blood test is due to start in mid-2021 and will involve 165,000 people.
The trial will include 140,000 individuals aged 50 to 79 years who were identified through their health records and who have no cancer symptoms. They will undergo blood tests annually for 3 years and will be referred for investigation if a test result is positive.
A second group will include 25,000 people with potential cancer symptoms. These patients will be offered the blood test to speed up their diagnosis after referral to a hospital via the normal channels.
The results of the pilot are expected in 2023. If successful, the test will be rolled out to one million individuals from 2024 to 2025.
The pilot trial is part of the NHS Long Term Plan, which aims to increase early detection of cancer. At present, around half of cancers in England are diagnosed in stage I or II; the NHS aims to increase this to 75% by 2028.
"The NHS has set itself an ambitious target," commented Peter Johnson, MD, PhD, national clinical director for cancer at NHS England and Improvement.
"Tests like this may help us get there far faster, and I am excited to see how this cutting-edge technology will work out as we test it in clinics across the NHS," he added.
Lord David Prior, chair of NHS England, noted that almost 200,000 people die from cancer in the United Kingdom every year and that "many of these people are diagnosed too late for treatment to be effective.
"This collaboration between the NHS and Grail offers the chance for a wide range of cancers to be diagnosed much earlier and could fundamentally change the outlook for people with cancer," he said.
However, some clinicians raised potential concerns.
Stephen Duffy, PhD, Center for Cancer Prevention, Queen Mary University of London, United Kingdom, described the pilot as "very exciting," but he cautioned: "We will need to find out just how early the test detects cancers and whether it can it be used in a way which minimizes anxiety from false positives."
Yong-Jie Lu, MD, PhD, also at Queen Mary University of London, said: "It is not clear how early it aims to catch cancer. For a cancer screen test, it needs very high specificity (>99%), otherwise it may end up in a similar situation as the PSA [prostate-specific antigen] test for prostate cancer, or even worse."
Mangesh Thorat, MD, Cancer Prevention Trials Unit, King's College London, United Kingdom, warned: "It is likely that for every testing round...there will be about 1000 false positive results, and the test may not be able to pinpoint the location of cancer in 3% to 4% of those with a true positive result, necessitating a range of imaging and other investigations in these participants."
No funding for the study has been declared. The investigators have disclosed no relevant financial relationships.
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