Multicancer early detection test fails in huge UK trial
February 23, 2026
Summary: The Galleri test did not demonstrate a statistically significant reduction in later-stage cancer diagnoses after three years of annual testing and follow-up.
The multicancer early detection (MCED) test Galleri has been promoted to employers to help decrease the toll of late-stage cancer. Detecting cancer at earlier stages could improve survival and quality of life. Some have also suggested it could lower medical costs. However, most recommended cancer screening tests save lives but increase total medical spending,
Detecting cancer at earlier stages could improve survival and quality of life, and some have inferred that it could lower medical costs, although currently all recommended screening tests save lives but increase total medical expense, A brief press release from Grail, the maker of the Galleri test, published last week indicates that a large randomized trial in the United Kingdom did not demonstrate a statistically significant shift toward earlier diagnoses among those tested.
England’s National Health Service (NHS) enrolled 142,000 people in a randomized trial to determine whether the test detects cancers earlier and whether it ultimately reduces mortality. The company press release indicates that there was an increase in earlier diagnoses among 12 prespecified deadly types of cancer that are often diagnosed when curative treatment is no longer possible, and that there was a decrease in the number of cancers that were diagnosed as medical emergencies. However, neither of these findings reached statistical significance.
Given the large size of the trial, failure to reach statistical significance suggests that any effect of the MCED test on these outcomes is likely to be small. The company says it plans to extend monitoring for an additional 6–12 months, and submitted Galleri for FDA approval last month.
The press release offers almost no detailed data and appears carefully worded to imply a benefit, even though the study found no statistically significant effect.
Grail share price dropped by over 50% in the day after the press release, although it remains 20% higher than a year earlier. The NHS saw an earlier version of this data over a year ago, and at that time decided not to further expand the clinical trial.
The Galleri test has higher specificity (fewer false positives) than a competing test, CancerGuard from Exact Sciences. Because the target population for MCED testing has a very low prevalence of undiagnosed cancer (less than 1%), even small differences in specificity can result in large differences in the number of false positives.
Sources: Galleri and Cancerguard
Here is a link to a post from earlier this month on the potential impact of sale of MCED tests directly to consumers.
Implications for employers:
The test has not demonstrated a statistically significant reduction in late-stage cancer diagnoses and has not shown a mortality benefit at this point
Employers offering this test as a benefit to plan members should expect an increase in total medical expense.
Employers considering coverage could limit eligibility to higher-risk individuals based on age or family history.
An alternative would be to devote resources to encouraging increased utilization currently recommended evidence-based cancer screening, which is underutilized.
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