NHS-Galleri: no fall in stage III–IV cancer after three rounds of multicancer blood testing

Design

Randomised controlled trial, three annual screening rounds

Population

142,250 people aged 50–77 in England

Primary outcome

Incidence of stage III or IV cancer across 12 prespecified types

Effect

IRR 1.03 (95% CI 0.92–1.14); stage IV IRR 0.86 (0.74–1.00)

In NHS-Galleri, 142,250 people aged 50 to 77 in England gave blood at up to three annual visits and were randomised to have it tested with a multicancer early-detection assay or stored untested. The primary end point was stage III or IV cancer among 12 prespecified cancer types after three rounds. It was published on 22 September.

The incidence of stage III or IV cancer did not differ (incidence rate ratio 1.03, 95% CI 0.92–1.14). The key secondary end point, stage IV cancer, was 14% lower (0.86, 0.74–1.00), with an interval reaching no difference. Fewer than 1% had trial-related adverse events, none serious.

The point of an early-detection test is to shift diagnoses to earlier stages, and on the primary measure that did not happen. The stage IV signal is a secondary end point that only just touches significance, and the investigators plan longer follow-up. No mortality data are reported. Patients may ask about these tests; current evidence does not support their use in place of, or in addition to, established screening.

• Advise patients that a multicancer blood test did not reduce late-stage cancer in the largest randomised trial so far.
• Keep established screening, such as cervical, breast and colorectal, as the recommended approach.
• Do not use a negative multicancer test to skip established screening or to dismiss symptoms.
• Expect further follow-up data on stage IV cancer and mortality before any change in practice.

Why it matters

Commercially available multicancer tests have now been tested in a large trial and missed their main target.

Don't overread it

The stage IV reduction is a secondary end point that only reaches the edge of significance.

The statistics, in plain English

An incidence rate ratio of 1.03 means late-stage cancer was as common with testing as without. The stage IV ratio of 0.86 has an upper limit of 1.00, so it may be a real effect or chance, and because it is a secondary end point it carries less weight.

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