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# A blood test found between a quarter and a third of cancers per screening round
- URL: https://www.coios.me/a-blood-test-found-between-a-quarter-and-a-third-of-cancers/
- Published: 2026-09-23T13:27:00.000Z
- Updated: 2026-09-23T21:35:38.000Z
- Description: In the NHS-Galleri trial of 142,250 adults aged 50 to 77, the multi-cancer blood test returned a positive result for about 1% of participants per round, with episode sensitivity of 26.7% to 37.2% for all cancers and positive predictive value falling from 58.0% to 45.8% across three rounds.
- Author: Daniel Ryan
- Tags: Healthcare today, Cancer, What changes behaviour at scale, United Kingdom, #peer-reviewed, #refines, #item, #source-2026-09

The NHS-Galleri trial randomised 142,250 people aged 50 to 77 to a blood-based multi-cancer early detection test added to usual care, or to usual care alone, and this paper reports prespecified secondary test-performance endpoints across three annual rounds in the intervention arm. Positive results were returned for 0.80% to 1.03% of participants per round, with 937 cancers detected by the test in total, episode sensitivity of 26.7% to 37.2% for all cancers and 47.6% to 63.4% for twelve prespecified types, and specificity of 99.50% to 99.60%. Positive predictive value fell across rounds from 58.0% to 45.8%.

*Why it is interesting: It measures what a multi-cancer blood test picks up in a randomised population programme rather than in case-control cohorts, and how that changes after the first round.*

Source

[Nature Medicine, 22 September 2026](https://doi.org/10.1038/s41591-026-04652-8?ref=coios.me)

DOI

10.1038/s41591-026-04652-8

Type

Peer-reviewed article

Design

Randomised controlled trial, 142,250 adults aged 50–77, three annual screening rounds; descriptive prespecified secondary endpoints

Verdict

Refines prior evidence

Driver

[Cancer](https://www.coios.me/d-cancer/)

Driver

[What changes behaviour at scale](https://www.coios.me/d-behaviour-change/)