Results from the first randomized controlled trial evaluating a multicancer early detection (MCED) blood test suggest that annual screening with the Galleri test may alter the stage at which cancers are diagnosed, reducing the burden of stage IV cancers. However, the study did not achieve its predefined primary endpoint of significantly reducing the incidence of late-stage (stage III or IV) cancers. The findings were presented at the 2026 ASCO Annual Meeting (Abstract LBA100).
Study Details
The NHS-Galleri trial enrolled 142,942 asymptomatic adults aged 50 to 79 years in the United Kingdom. Participants were randomly assigned to receive either annual Galleri testing in addition to standard cancer screening or standard screening alone over a 3-year period. The Galleri assay analyzes circulating cell-free DNA in blood to identify cancer-associated methylation patterns and predict the cancer’s tissue of origin.
The trial was designed to determine whether adding Galleri testing to existing screening programs could shift the diagnoses of 12 prespecified cancers toward earlier stages. While the reduction in stage III and IV diagnoses among these cancers was not statistically significant, investigators observed evidence of stage shifting in the intervention group. Compared with controls, participants undergoing Galleri screening experienced a 14% reduction in stage IV diagnoses and a 19% increase in cancers diagnosed at stages I, II, or III.
Lead study author Charles Swanton, MD, PhD, of The Francis Crick Institute and University College London Cancer Institute, described the study as a milestone for the field. “This is the first randomized controlled trial of a multi-cancer early detection test to report results, and it represents a landmark achievement for participants and the UK’s National Health Service,” he said. “The trial demonstrates that annual multi-cancer early detection testing is feasible at scale within a national health system and can increase the number of cancers detected through screening, including many for which no organized program currently exists.”
Key Takeaways
Across all cancer types, 3,637 cancers were diagnosed in the Galleri group compared with 3,400 in the control group. Screening-detected cancers were substantially more common among participants who underwent Galleri testing, with 1,173 cancers identified through screening compared with 290 in the control group.
Investigators also reported reductions in cancers detected outside of screening settings. Across all cancer types, the Galleri group experienced 21% fewer clinically detected cancers and 20% fewer cancers diagnosed during emergency presentations—circumstances often associated with more advanced disease and poorer outcomes.
Although the findings suggest that MCED screening may reduce the incidence of stage IV disease, it is not yet known whether all cancers detected by Galleri would have become clinically significant or whether earlier detection ultimately improves survival. Continued follow-up of trial participants will evaluate long-term outcomes, including cancer mortality and overall survival, as well as the cost-effectiveness of routine MCED screening.
DISCLOSURE: For full disclosures of the study authors, visit coi.asco.org.
