Blood test to detect 50 types of cancer fails to meet key outcome in NHS trial
A blood test that aims to detect 50 types of cancer has failed to meet its primary endpoint in a large NHS trial of its use.
Results from NHS study of the Galleri test have not yet been published in a journal but were announced to investors of the Grail, the company behind the test.
The ‘landmark’ £150 million NHS trial was set up to test annual multi-cancer screening with the Galleri test over three years in 142,000 participants aged 50 to 77 to ‘inform national screening’.
Announcing the topline findings, the company said the primary endpoint of statistically significant stage III-IV reduction was not observed.
‘However, there was a favourable trend toward fewer stage III-IV cancers in a pre-specified group of 12 deadly cancers in the intervention arm after the prevalent screening round,’ the release continued.
The company pointed to other indicators from the trial that suggested a benefit of using the test.
There was a ‘meaningful reduction in stage IV diagnoses’ across the pre-specified group of 12 deadly cancers, the announcement said.
And doing annual screening with the test in addition to any usual screening people would be eligible for led to a ‘four-fold improvement in the overall cancer detection rate for breast, colorectal, cervical and high-risk lung cancer’.
There had also been a ‘substantial reduction’ in the number of cancers detected clinically through emergency presentation, it continued.
Use of the test has been controversial with much debate about how it might be used in practice.
Some had warned data was showing the test was not performing as well as expected.
The company said the trial had shown the ‘strongest evidence to date’ that use of the test ‘can shift the stage at which cancers are detected at a population level’.
Professor Charles Swanton, thoracic medical oncologist at University College Hospital, London and a chief investigator of the NHS-Galleri trial, said: ‘As an oncologist, I see how profound the difference is between stage III and stage IV disease.’
He added that reducing the proportion of patients diagnosed with metastatic disease is not merely a statistical aim, ‘it dramatically increases the number of patients for whom eradication of disease and cure is possible’.
But Professor Richard Houlston, head of the Division of Genetics and Epidemiology, at the Institute of Cancer Research, said: ‘The press release around the NHS-Galleri trial highlights the familiar misconception that a favourable trend is almost as persuasive as a statistically robust result.
‘GRAIL’s press release emphasises reduced Stage IV and increased Stage I–II diagnoses, yet the trial did not achieve a statistically significant reduction in combined Stage III–IV cancers, its primary endpoint.’
He said when the main outcome is not met, selectively highlighting secondary or subgroup findings should be seen as ‘hypothesis-generating, not proof of benefit’.
‘Moreover “stage shift” itself may be an unreliable surrogate for real patient benefit, as increased early-stage detection can reflect overdiagnosis or indolent disease that would never have caused harm.
‘Without mortality data and a transparent account of harms, including false positives, unnecessary procedures, and opportunity cost, claims of population benefit from multi-cancer early detection remain speculative.’
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