American biotech company developing multi-cancer blood tests. Its test, called Galleri, aims to detect over 50 types of cancer from a single blood draw. Galleri has been on the market since 2021 and is the most widely used and studied of such tests.
Galleri analyses fragments of DNA shed by cancer cells in the blood, looking for signs that chemical tags have been added to them—a process known as methylation—which alters which genes are switched on and off. Its method of doing so destroys most of the DNA, limiting what can be gleaned from a sample. According to Anna Schuh, who leads molecular diagnostics research at Oxford University's Department of Oncology, GRAIL's technology is "somewhat outdated now".
In October 2025 GRAIL announced results from a trial of 23,000 people aged 50 or older. Galleri spotted around 40% of the cancers diagnosed over the following year (of which half were early-stage) and usually identified the right part of the body. It missed 60% of cancers and generated false alarms: it threw up a cancer "signal" in about 1 in 107 participants, and roughly two in five of those alarms proved wrong.
On February 19th 2026 the company announced that Galleri had failed its latest trial. Over three years, 142,000 people aged 50 to 77 were studied: half were screened with Galleri in addition to standard tests. The hope was that it would spot enough early-stage cancers to reduce the number of late-stage diagnoses. It did not. In a trial of 6,000 patients in England referred for cancer investigations because of worrying symptoms, a third of presumed false alarms were diagnosed with cancer when followed for an additional 15 months, suggesting the test was detecting some cancers before they were advanced enough to be spotted by standard methods.
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