Multi-Cancer Blood Test Fails Primary Objective in NHS Trial
A blood test designed to detect multiple types of cancer has not met its primary goal in a large NHS trial, the developing company has revealed.
The Galleri blood test is currently being evaluated on 142,000 NHS patients with the aim of identifying cancers early to improve survival rates.
Despite the test missing its main target, the company behind it, Grail, indicated that data still showed encouraging signs that some of the most aggressive cancers might be prevented.
However, researchers have cautioned that any benefits from the test "remain speculative" until there is clear evidence it saves lives, and the NHS stated it is reviewing the results "carefully."
How the Test Works and Trial Goals
The blood test detects fragments of DNA, or genetic material, that have been shed into the bloodstream by tumours.
The goal is to identify up to 50 different cancer types before symptoms appear.
When the trial began, NHS England described the test as "the beginning of a revolution."
The trial was designed to assess whether screening blood samples could reduce the number of cancers diagnosed at later stages, which are typically more difficult to treat.
Stage three cancers indicate that a tumour has begun to spread locally, while stage four cancers have spread to distant organs.
Trial Results and Market Impact
The full data from the three-year NHS trial has not yet been published, but Grail has provided an update to investors.
It stated:
"While there was a trend towards reduction in combined stage three and four [cancers], the trial did not meet the primary endpoint."
Following this announcement, Grail, a US pharmaceutical company, saw its market value halve, with its share price falling back to levels last seen at the end of the previous summer.
Nonetheless, further analysis focusing solely on stage four cancers showed a roughly 20% decrease in these cases within the study, suggesting that the most lethal cancers were being detected earlier.
Debate Over Significance of Findings
The significance of this secondary finding, given it was not the primary focus of the trial, has sparked considerable discussion.
Professor Charles Swanton, who is leading the trials within the NHS, expressed optimism about the reduction in stage four cancers.
"I've been working in oncology for 20 years and the key, in my mind, is to reduce stage four because these are the cancers we cannot cure,"he said.
Conversely, other experts emphasize the importance of focusing on the primary endpoint, as that was the trial's main objective.
Professor Richard Houlston, from the Institute of Cancer Research, commented:
"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,"he said.
Next Steps and NHS Response
The complete data set is expected to be presented at the American Society of Clinical Oncology meeting later this year.
An NHS spokesperson stated:
"This evidence is an important step and the NHS will carefully study the full results from this major trial in the coming months to help determine how blood tests like this could be used in the future."
