February 20, 2026

expert reaction to press release from GRAIL on the topline findings of the NHS-Galleri trial

Scientists comment on topline findings of the NHS Galleri trial, published by GRAIL. 

Professor Richard Houlston, Head of the Division of Genetics and Epidemiology, 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. 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.”

https://grail.com/press-releases/landmark-nhs-galleri-trial-demonstrates-a-substantial-reduction-in-stage-iv-cancer-diagnoses-increased-stage-i-and-ii-detection-of-deadly-cancers-and-four-fold-higher-cancer-detection-rate/

Declared interests

Prof Richard Houlston: “I have no conflicts of interest”