British Medical JournalGalleri Promises to Detect Multiple Cancers—but New Evidence Casts Doubt on this Much-Hyped Blood Test

Galleri Blood Test for Early Cancer Detection Faces Scrutiny Amid Concerns Over Efficacy and Trial Design

The Galleri blood test, developed by Grail to detect multiple cancers early, is undergoing a £150 million trial in England. However, new evidence casts doubt on its effectiveness as a screening tool. Experts are questioning the test’s sensitivity, especially for early-stage cancers, and raising concerns about the trial’s design and ethical implications.

Key Points:

• Galleri claims to detect more than 50 types of cancer from a single blood sample.
• The NHS is running a £150 million trial involving more than 100,000 participants in England.
• Experts argue that Galleri has been overhyped and that the current trial is unethical.
• Earlier studies showed low sensitivity: 43.9% for stage I-III cancers and only 16.8% for stage I cancers.
• Leaked documents reveal “serious concerns” from Mike Richards, chair of the UK National Screening Committee, about the trial’s ability to provide sufficient evidence.
• The NHS has committed to buying one million tests after the first stage of the trial and potentially five million more by 2030 if certain criteria are met.
• Grail is facing a class action lawsuit in the US, with investors claiming the company exaggerated Galleri’s effectiveness.
• The trial’s success criteria include a positive predictive value over 30% and a 30% reduction in stage IV cancers in the intervention arm.
• Experts argue that demonstrating a shift in cancer stage distribution does not necessarily indicate improved survival.
• A 2023 Lancet study suggests even lower sensitivity in a screening population, with 62% false positives.
• Concerns have been raised about the close relationship between key government figures and Grail.
• The UK National Screening Committee has expressed major disquiet regarding the evaluation process for Galleri.

“With a sensitivity for stage I disease of less than 20% overall and only 44% for all stage I-III cancers diagnosed through other tests, I do not think a trial is ethical.”
– Paul Pharoah, Professor of Cancer Epidemiology at the Cedars-Sinai Medical Center, Los Angeles

More on Medical Ethics