Clinical resources

Information for healthcare professionals

The information on this page is designed for healthcare professionals, such as general practitioners and hospital doctors in areas where the NHS-Galleri trial is taking place, to provide information about the trial. The target audiences are healthcare professionals and organisations supporting the trial.


The NHS-Galleri trial is a prospective, randomised, controlled trial to assess the performance and clinical utility of a multi-cancer early detection test (Galleri®) for population screening in the UK when added to standard of care. The trial is designed to establish if screening with the Galleri test reduces the incidence of late stage cancer when used in an asymptomatic population in combination with existing NHS cancer screening programmes.[1]

Around 140,000 people have volunteered to take part in the trial after receiving an invitation letter from the NHS. Participants (age 50–77 years with no history of invasive cancer in the past three years) are invited to attend three appointments over two years, about 12 months apart. At each appointment, participants are asked to give a blood sample and complete a health questionnaire.

The trial is run by the Cancer Research UK & King’s College London Cancer Prevention Trials Unit on behalf of GRAIL Bio UK Ltd. (GRAIL) and NHS England. GRAIL is the commercial sponsor of the NHS-Galleri trial. GRAIL is a branch of GRAIL, LLC, a company based in the United States that developed the Galleri test.

Trial design

The NHS-Galleri trial is a prospective, randomised, controlled trial blinded at the point of randomisation.

Following baseline blood sample collection, participants were randomised (1:1) to either:

  • Intervention arm — blood is sent for analysis using the Galleri test.
  • Control arm — blood is stored (and may be used in future analyses).

Only participants in the intervention arm who have a cancer signal detected have results returned. These participants are referred to the NHS for investigations and potential treatment. Remaining participants in both arms stay blinded and return for their next trial appointment. Participants are reminded to continue to attend NHS cancer screening programmes and to seek help for new or unusual symptoms.

Referral to the NHS

Referrals to the NHS are managed by the trial team’s research nurses. NHS England have developed guidance to support Trusts and local services. Guidance for NHS-Galleri Trial Referrals’ can be accessed on FutureNHS, or via your local Cancer Alliance.

Receiving Trusts are responsible for the clinical management of the participants referred. Any diagnostic work up is outside of the trial and should be conducted according to national and local guidance for urgent suspected cancer referrals (two-week wait or rapid diagnostic pathways). Clinical judgement should be applied at all steps, including consideration of the patient’s overall fitness and likelihood of benefit from further investigation or treatment.


  1. Neal, RN et al. Cell-Free DNA–Based Multi-Cancer Early Detection Test in an Asymptomatic Screening Population (NHS-Galleri): Design of a Pragmatic, Prospective Randomised Controlled Trial. Cancers 2022;14:4818. DOI: 10.3390/cancers14194818. Back