This multi-cancer blood test might not be useful after all
31 May 2026

A groundbreaking blood test, touted as a major advancement in oncology, has failed to achieve its primary goal in a large-scale clinical trial.

The study involved 142,942 National Health Service (NHS) patients in the UK and aimed at determining if the multi-cancer early detection test Galleri could help diagnose cancers at earlier stages.

However, it didn't meet its main objective of reducing late-stage cancer diagnoses.

How the trial was conducted
Trial details

The trial, the first-ever randomized controlled study of a multi-cancer early detection (MCED) test, was presented at the American Society of Clinical Oncology's annual meeting in Chicago.

It involved 142,942 asymptomatic participants aged between 50 and 77.

Each participant provided a blood sample once a year for three years and underwent standard cancer screening tests.

Half of them had their blood samples analyzed using the Galleri test while the other half served as controls.

'Trial flopped' says senior cancer expert
Expert opinions

Dr. Julie Gralow, ASCO's chief medical officer, acknowledged some positive trends toward tumor downstaging but stressed that the trial didn't statistically reduce late-stage cancers by its predefined primary endpoint.

A senior cancer expert who spoke to The Guardian on condition of anonymity was more blunt in their assessment saying "the trial flopped."

The study's main goal was to show a reduction in late-stage cancers overall, which it failed to achieve.

Grail encouraged by findings
Mixed results

Despite the setback, Grail, the California-based company behind the test, was encouraged by other findings from the trial.

They highlighted data showing a 14% reduction in stage four cancers alone, indicating that some of the deadliest forms of cancer were being detected at an earlier stage.

However, Professor Richard Houlston from London's Institute of Cancer Research cautioned against interpreting these secondary findings too positively as they still remain uncertain and should be interpreted cautiously.

NHS waiting for data
Next steps

Professor Peter Johnson, the National Clinical Director for cancer at NHS England, said they look forward to seeing the data from the trial in detail.

He added this would help them make decisions on what it could mean for the NHS in future.

The failure to meet its primary endpoint is a major concern here and mortality outcomes will be available in a couple of years.