NHS-Galleri trial reduces stage four diagnoses

As well as demonstrating a substantial reduction in stage four cancer diagnoses, the test increased stage one and two detections of deadly cancers, and four-fold higher cancer detection rate. The primary endpoint of statistically significant combined stage three-four reduction was not met, but a favourable trend was observed over time.

The clinical performance of Galleri has been rigorously established in several studies, and the NHS-Galleri trial was designed to demonstrate population-level impact through the reduction of late-stage cancer diagnoses and increased cancer detection rate within the NHS to inform a decision about a national screening programme in England. For the US market, the Galleri premarket approval application pending review by the FDA also includes metrics from the NHS-Galleri trial that are focused on test performance, clinical validation, and the clinical benefit of detection at stages one-three, including reduction in stage four cancer diagnoses.  

Key trial results include:

• The primary endpoint of statistically significant stage three-four reduction was not observed. However, there was a favourable trend toward fewer stage three-four cancers in a pre-specified group of 12 deadly cancers* in the intervention arm after the prevalent screening round. 
• Adding Galleri to standard of care screening resulted in a substantial and clinically meaningful reduction in stage four diagnoses compared with standard of care alone across the pre-specified group of 12 deadly cancers. Stage four diagnoses in these cancers decreased with each year of sequential screening, with a greater than 20% reduction in the second and third rounds. Similar reductions were observed across all cancers.
• Annual screening with the Galleri test plus standard of care screening resulted in a four-fold improvement in the overall cancer detection rate compared to standard of care screening alone in England for breast, colorectal, cervical and high-risk lung cancer.
• Substantial increase in the absolute number of stage one-two cancers in the 12 pre-specified deadly cancer types that are typically found in late stages were observed in the intervention arm. 
• Screening with the Galleri test resulted in a substantial reduction in the number of cancers detected clinically through emergency presentation, which are associated with significantly higher mortality and healthcare costs. 

“The NHS-Galleri trial provides the strongest evidence to date that multi-cancer early detection can shift the stage at which cancers are detected at a population level,” said Bob Ragusa, Chief Executive Officer at GRAIL. “We are excited to see the substantial reduction in stage four cancer diagnoses, as well as the continued strong Galleri test performance metrics. Based on these promising data, as well as the exciting PATHFINDER 2 results, we are expanding our field-based sales and medical teams to bolster our education efforts and support growing demand.”

“As an oncologist, I see how profound the difference is between stage three and stage four disease,” said Professor Charles Swanton, thoracic medical oncologist at University College Hospital, London and one of the NHS-Galleri trial’s chief investigators. “When cancer is detected before distant metastatic spread, we can often treat with curative intent, combining surgery, radiotherapy, and systemic therapy in an effort to eradicate all disease. Once distant metastases are established, treatment typically shifts toward long-term disease control and symptom management; durable cures become uncommon in most solid tumours. Reducing the proportion of patients diagnosed with metastatic disease is therefore not merely a statistical aim, it dramatically increases the number of patients for whom eradication of disease and cure is possible.”

The Galleri test’s performance – positive predictive value (PPV), specificity and Cancer Signal of Origin (CSO) accuracy – was consistent with the range previously reported from GRAIL’s North American studies. 

Importantly, no serious safety concerns were reported in participants who received the Galleri test in the NHS-Galleri trial.

“The design of the NHS-Galleri trial was informed by a growing body of evidence showing that, across multiple cancer types, reductions in late-stage disease are strongly associated with reductions in cancer mortality. The reduction in stage four cancer diagnoses is an exciting and critically important outcome, which we believe can lead to more effective intervention for patients, particularly given the substantial and growing arsenal of effective treatments for many stage three cancers,” said Sir Harpal Kumar, Chief Scientific Officer and President, International at GRAIL. “We are deeply grateful to the more than 142,000 participants who took part in this study, as well as to the NHS, the Cancer Prevention Trials Unit at Queen Mary University of London, Cancer Alliances, investigators, and clinical teams whose dedication made this landmark trial possible. Our learnings from this trial enrich our understanding of cancer biology, multi-cancer screening, and the importance of implementation, particularly ensuring rapid and thorough diagnostic investigation after a positive test result.”

Additional analyses are underway to better understand these rich data, and detailed results will be submitted for presentation at the ASCO 2026 Annual Meeting. Of note, there was a higher than anticipated incidence of stage three cancers in the NHS-Galleri trial. In both the US and the NHS data, the time to diagnostic resolution appears to improve over time as physicians gain experience with the Galleri test and diagnostic workup. The number and distribution of cancer stages across screening rounds suggests the potential for a stronger effect with longer follow up as data matures, and GRAIL plans to extend the trial’s follow up period by 6-12 months. 

*The 12 cancer types include anus, bladder, colorectal, oesophagus, head and neck, liver/bile duct, lung, lymphoma, myeloma/plasma cell neoplasm, ovary, pancreas, stomach.