Results from the NHS-Galleri study show a 26% reduction in metastatic cancer diagnoses by the third round of screening.
GRAIL announced clinical utility, performance, and safety results from the NHS-Galleri trial during the 2026 American Society of Clinical Oncology Annual Meeting.
The randomized, controlled trial evaluated annual screening with the Galleri multi-cancer early detection (MCED) test in 142,250 participants aged 50 to 77 in England’s National Health Service (NHS).
While the trial did not meet its combined primary endpoint of reducing Stage III and IV diagnoses in aggregate within a one-year follow-up window, secondary endpoints showed a decrease in Stage IV cancers. Stage IV diagnoses for 12 prespecified cancers fell by 22% in the second screening round and 26% in the third round when the test was added to standard care.
“The NHS-Galleri trial provides a wealth of data that support the use of the Galleri test to reduce the burden of metastatic Stage IV cancer and increase the number of cancers found earlier through screening at population scale,” says Josh Ofman, MD, MSHS, president and CEO-elect at GRAIL, in a release.
Shift to Earlier Stages
According to the results, Stage I and II diagnoses increased by 16% for the 12 prespecified cancer types after three rounds of screening. This included increases in cancers often diagnosed late, such as ovarian, esophageal, pancreatic, and liver cancers.
The increase in Stage III diagnoses outweighed the decrease in Stage IV during the initial screening round. Sir Harpal Kumar, chief scientific officer and president, global clinical and medical affairs at GRAIL, says the Stage III increase was partly driven by Stage IV cancers being shifted to earlier stages, in a release.
“Finding these cancers earlier means we can start treating those patients with the urgency needed and, in many cases, with the opportunity of curative intent,” says Sir Harpal Kumar, chief scientific officer and president, global clinical and medical affairs at GRAIL, in a release.
Adding the blood test to standard screenings resulted in a four-fold increase in screen-detected cancers. Additionally, diagnoses made through emergency presentations decreased by 25%, according to the trial data.
Test Performance and Safety
The trial reported a specificity of 99.55%, resulting in a false positive rate of 0.45%. The positive predictive value (PPV) was 52.0% overall and 58.0% in the first screening round. Cancer signal of origin (CSO) accuracy reached 92.5%.
Episode sensitivity, which measures the ability to detect cancers diagnosed within 12 months of a blood draw, was 54.7% for the 12 prespecified cancer types and 30.7% across all cancer types.
“Galleri represents a potential transformational shift in cancer detection, moving us to a more comprehensive proactive approach,” says Kumar in a release.
The study reported no serious related adverse events, according to the press release.
“The Stage IV reduction is clinically meaningful because for many cancers there is a real gulf in outlook between a Stage IV diagnosis and one caught earlier,” says Charles Swanton, PhD, thoracic medical oncologist at University College London Hospital and one of the trial’s chief investigators, in a release.
The 12 prespecified cancers in the study represent approximately two-thirds of cancer deaths in the United States and England. Exploratory analysis showed Stage IV diagnoses were reduced by 57.1% in esophageal cancer and 34.4% in colorectal cancer during incident rounds.
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