NHS-Galleri: a multicancer blood test did not lower stage III or IV cancer incidence

Design

Randomised controlled trial, tested blood vs stored blood, three annual rounds

Population

142,250 people aged 50 to 77 in England

Primary outcome

Incidence of stage III or IV cancer among 12 prespecified cancer types

Effect

Rate ratio 1.03 (95% CI 0.92 to 1.14), P=0.63; stage IV rate ratio 0.86 (0.74 to 1.00)

In this randomised trial in England, blood was drawn from people aged 50 to 77 at up to three annual visits. After baseline collection, 71,122 were assigned to have their blood tested for multiple cancers and 71,128 to have it stored. Everyone continued usual care.

The primary end point was stage III or IV cancer among 12 prespecified cancer types. After three screening rounds and at least 12 months of follow-up, the incidence rate did not differ (rate ratio 1.03, 95% CI 0.92 to 1.14; P=0.63). For stage IV cancer, a key secondary end point, the rate ratio was 0.86 (0.74 to 1.00). Fewer than 1% had trial-related adverse events and none were serious.

The authors state that further follow-up is warranted to see how the stage III or IV and stage IV differences evolve. For now, the primary question, whether adding this test lowers late-stage diagnoses, has a null answer.

• Do not offer multicancer blood tests as a replacement for established screening such as breast, cervical and colorectal programmes.
• In this trial, adding the test did not reduce stage III or IV cancer incidence across 12 prespecified cancer types.
• A stage IV rate ratio of 0.86 (0.74 to 1.00) is a secondary signal that the authors want followed up.
• Patients asking about privately marketed tests can be told the primary outcome did not improve and longer follow-up is planned.

Why it matters

It tests whether detecting more cancers early translates into fewer late-stage diagnoses, which is the assumption behind these tests.

Don't overread it

Follow-up continues, and a trial in England does not settle test performance in other populations or for individual cancer types.

The statistics, in plain English

A rate ratio of 1.03 with an interval of 0.92 to 1.14 spans no difference, so the data show no detectable benefit on the primary end point. The stage IV interval touches 1.00, which makes it borderline and secondary, and it should not be read as a positive result.

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