- Design
- Randomised controlled screening trial
- Population
- 142,250 people aged 50–77 in England
- Primary outcome
- Stage III or IV cancer across 12 cancer types after three rounds
- Effect
- IRR 1.03 (0.92–1.14); stage IV IRR 0.86 (0.74–1.00)
NHS-Galleri, published on 22 September, randomised 142,250 people aged 50 to 77 in England after a baseline blood draw. Blood was tested annually for three rounds in the intervention group and stored in the control group. The primary end point was stage III or IV cancer across 12 prespecified types.
After three rounds and at least 12 months of follow-up, the incidence of stage III or IV cancer did not differ (IRR 1.03, 95% CI 0.92–1.14). Stage IV cancer, a key secondary end point, was lower in the tested group with an interval reaching 1.00 (IRR 0.86, 0.74–1.00). Trial-related adverse events affected fewer than 1%, none serious.
The aim of screening is to shift diagnosis to an earlier stage, and on its primary end point this test did not. The stage IV signal is borderline and secondary. Further follow-up is planned, but on current evidence these tests do not belong in routine screening, and the trial was funded by the test's manufacturer.
- Do not recommend multicancer early-detection blood tests for routine screening on current evidence.
- Explain to patients that the largest trial found no fall in late-stage cancer after three rounds.
- Continue organ-specific screening with proven benefit.
- Watch for longer follow-up, as the stage IV result is borderline.
Why it matters
Detecting cancer in blood is not the same as diagnosing it early enough to change its stage.
Don't overread it
The stage IV reduction is a borderline secondary finding and may change with follow-up.
The statistics, in plain English
An IRR of 1.03 with an interval of 0.92–1.14 means no detectable difference. The stage IV IRR of 0.86 has an upper limit of exactly 1.00, so it is at the edge of significance and secondary.
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