Landmark NHS-Galleri Trial Demonstrates Substantial Shift Toward Early Cancer Detection with Multi-Cancer Blood Test

England’s National Health Service (NHS) has reported promising trial results from the NHS-Galleri trial, including earlier-stage diagnoses and reduced late-stage presentations for several high-mortality cancers.* The NHS-Galleri trial is a large-scale, randomized controlled study evaluating the Galleri® multi-cancer early detection (MCED) liquid biopsy blood test. By detecting cancer-associated methylation patterns in cell-free DNA, the test can identify many cancers before they become symptomatic and often before standard screenings, primarily for high-risk individuals.

The trial, funded by GRAIL, the National Health Service (NHS), and the National Institute for Health and Care Research (NIHR), with findings presented by GRAIL, offers significant insights into the clinical utility of population-wide blood-based cancer screening and may inform future implementation of national screening programs.

The NHS-Galleri trial enrolled over 142,000 asymptomatic participants** aged 50–77 years from a demographically representative cohort in England. Participants were randomized to receive annual Galleri blood tests in addition to standard-of-care screening or standard-of-care alone, with three blood draws over two years, spaced approximately 12 months apart. The study focused on the impact of MCED screening on the incidence and stage distribution of cancers, particularly across a prespecified group of 12 deadly cancer types that collectively account for approximately two-thirds of cancer deaths in the UK and US.

Study findings

• Reduction in Advanced-Stage Diagnoses: While the primary endpoint—a statistically significant reduction in combined Stage III-IV diagnoses—was not met, the intervention arm showed a favorable trend toward fewer advanced cancers over time, particularly among the 12 prespecified high-mortality cancers. Notably, a substantial and clinically meaningful reduction in Stage IV diagnoses was observed, exceeding 20% in the second and third screening rounds.
• Increased Early-Stage Detection: The intervention arm experienced a marked increase in Stage I-II diagnoses among the 12 deadly cancer types, indicating a stage shift toward earlier detection, which is associated with improved prognosis.
• Overall Cancer Detection Rate: Annual MCED screening resulted in a four-fold increase in the overall cancer detection rate for breast, colorectal, cervical, and high-risk lung cancers versus standard screening alone.
• Reduction in Emergency Presentations: Screening with Galleri significantly decreased the number of cancers first detected through emergency presentations, an important outcome given the higher mortality and healthcare costs associated with such diagnoses.

Clinical and Public Health Implications
The study results did not reveal serious safety concerns among participants who received the Galleri test. The test’s positive predictive value, specificity, and cancer signal origin (CSO) accuracy were consistent with prior North American studies, with specificity exceeding 98% and a low false positive rate.

“Detecting cancer before distant metastatic spread allows for curative-intent treatment. These results suggest multi-cancer early detection can meaningfully increase the number of patients eligible for potentially curative therapy,” noted Professor Charles Swanton, MD, Ph.D., a renowned thoracic medical oncologist at University College London Hospitals (UCLH) and the NHS-Galleri trial chief investigator.

“The reduction in Stage IV diagnoses is an exciting and critically important outcome. Our learnings from this trial advance our understanding of MCED’s role in population screening and the pathway to implementation,” added Sir Harpal Kumar, Chief Scientific Officer at GRAIL, highlighting the broader impact of the trial and study results.

Study Limitations and Next Steps
The trial observed a higher-than-anticipated incidence of Stage III cancers, and time to diagnostic resolution improved as clinicians became more familiar with the test. Ongoing analyses will further elucidate the impact of MCED screening, and detailed results will be presented at the ASCO 2026 Annual Meeting held May 29-June 2, 2026, in Chicago, IL.

GRAIL plans to extend trial follow-up by 6–12 months to capture longer-term outcomes.

Broader Context
A recent systematic review funded by the NIHR Health Technology Assessment program*** identified 36 studies evaluating blood-based MCED tests. While all available tests, including Galleri, demonstrated high specificity (>96%), sensitivity for early-stage detection was variable and generally lower than for advanced cancers. Most studies suffered from methodological limitations, including inadequate follow-up of negative results and limited patient-relevant outcome data (e.g., mortality, quality of life). The NHS-Galleri trial is the first and largest prospective randomized controlled trial to assess the utility of MCED in a real-world, asymptomatic screening population.

The NHS-Galleri trial also established a standardized referral pathway for positive Galleri results, integrating seamlessly with existing NHS urgent suspected cancer pathways. This approach may serve as a model for future MCED screening program integration, minimizing burden on primary care and expediting diagnostic workup.

Overall, the NHS-Galleri trial provides robust evidence that population-based, blood-based multi-cancer early detection screening can shift cancer diagnoses toward earlier, more treatable stages and reduce the burden of late-stage disease. While further research is needed to fully elucidate the impact on mortality, quality of life, and health system outcomes, these findings support the potential role of MCED in population cancer screening and highlight the importance of ongoing evaluation, patient-centered outcomes, and healthcare system readiness.

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Note: * The Galleri multi-cancer early detection (MCED) test is a blood-based screening assay designed to detect more than 50 types of cancer prior to the onset of symptoms. The test is intended to identify cancers at an earlier, potentially more treatable stage. Clinical studies have demonstrated Galleri’s performance in individuals undergoing cancer screening, and published data suggest that when Galleri is used in addition to standard screening for breast, cervical, colorectal, and lung cancers, the overall cancer detection rate increases substantially. The test also provides information on the likely tissue of origin to help inform subsequent diagnostic evaluation. Galleri requires a prescription from a licensed healthcare provider and is intended to complement, not replace, recommended cancer screening modalities such as mammography, colonoscopy, prostate-specific antigen (PSA) testing, or cervical cancer screening. Current recommendations suggest consideration of Galleri for adults at elevated risk for cancer, including those aged 50 and above.

** The authors of the study thank the more than 142,000 participants, NHS partners, and the Cancer Prevention Trials Unit at Queen Mary University of London for their contributions.

*** The Health Technology Assessment (HTA) program, part of the National Institute for Health Research (NIHR), was established in 1993. It produces high-quality research information on the effectiveness, costs, and broader impact of health technologies for those who use, manage, and provide care in the NHS.

Clinical trial
Does Screening With the Galleri Test in the NHS Reduce the Likelihood of a Late-stage Cancer Diagnosis in an Asymptomatic Population? A Randomised Clinical Trial (NHS-Galleri) – ClinicalTrials.gov ID NCT05611632 (ISRCTN91431511)

References
[1] US Galleri® Website. Online. Last accessed March 20, 2026.
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