The NHS-Galleri trial is a research trial to see how well the Galleri blood test works in the NHS. The aim of the trial is to see if using the Galleri test alongside existing cancer screening can help to find cancer early. Finding cancer early often means it is easier to treat.
Over 140,000 volunteers aged 50–77 have registered to take part in the trial after receiving an invitation letter from the NHS. Participants have been invited to attend three appointments over two years, about 12 months apart.
Although appointments are complete, data is still being collected to help with the research. Final trial results are expected to be available from 2026 but may take longer.
Search for the latest results of the NHS Galleri Trial:
Key findings and trial status
Interim NHS results: NHS England stated in May 2024 that the interim results from the first year of the NHS trial were not “compelling enough” to proceed with a large-scale program at that time.
US PATHFINDER 2 trial results: A separate, parallel trial in the US, PATHFINDER 2, released topline data in October 2025 showing Galleri increased cancer detection by over seven-fold when used alongside existing screenings.
Final results awaited: The full, three-year NHS-Galleri trial is ongoing, with final results expected in 2026.
Trial purpose: The trial’s primary goal is to determine if the Galleri test can help the NHS detect cancer earlier in the population and to assess the best way to refer patients with a positive signal for further investigation.
What this means for participants
No individual results: Participants in the NHS trial will not receive their individual test results, regardless of whether they were in the test or control group. This is to maintain the trial’s integrity.
Future use: The blood samples from the trial will not be used for any other purpose. However, it is possible that samples from the control group will be tested in the future for research purposes.
Not a diagnostic test: A positive result on the Galleri test is not a definitive cancer diagnosis. It indicates that a cancer signal has been detected, and further medical investigation is required.
What the Galleri test does
Detects cancer signals: The Galleri test identifies fragments of cancer DNA circulating in the blood to detect a “cancer signal”.
Detects multiple cancer types: It is designed to detect a common signal shared by over 50 different types of cancer, including many for which there is no current national screening program (e.g., lung, stomach, pancreatic, ovarian).
Predicts cancer origin: The test can predict the origin of the cancer signal in the body with reasonable accuracy.