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The first study to return Galleri results to people without symptoms and follow what happened next; its results appeared in The Lancet in 2023.
PATHFINDER (NCT04241796) is a single-arm interventional study sponsored by GRAIL, Inc. Its primary outcomes were the number and types of diagnostic tests, and the time needed, to reach a diagnosis after a cancer-signal-detected result. The results paper (Schrag 2023) reports a signal in 92 of 6,621 analysed participants, of whom 35 had cancer.
The registry record, read on 29 October 2026, gives its status as completed, with 6,662 participants enrolled, a start on 12 December 2019 and primary completion on 1 December 2021.
A multi-cancer blood test can be run in ordinary clinics, and most positive results can be resolved with imaging. But six in ten positives are false alarms that take months to resolve, and the test misses most cancers. Whether it reduces late-stage cancer or deaths is unknown; that requires randomised trials.
Set beside the result (35 cancers among 92 positives, positive predictive value 38%), it shows the test found fewer cancers than its makers had modelled.
Shares PATHFINDER 2, PATHFINDER: the first prospective test of a multi-cancer blood test in people without symptoms, GRAIL, Galleri.
Shares GRAIL, Galleri, Multi-cancer early detection (MCED), Liquid biopsy (ctDNA).
Shares GRAIL, Galleri, Multi-cancer early detection (MCED), Liquid biopsy (ctDNA).
Shares GRAIL, Galleri, Multi-cancer early detection (MCED), Liquid biopsy (ctDNA).
Shares GRAIL, Galleri, Multi-cancer early detection (MCED), Liquid biopsy (ctDNA).
Shares GRAIL, Galleri, Multi-cancer early detection (MCED), Liquid biopsy (ctDNA).
Shares GRAIL, Galleri, Multi-cancer early detection (MCED), Liquid biopsy (ctDNA).
Shares PATHFINDER 2, PATHFINDER: the first prospective test of a multi-cancer blood test in people without symptoms, Galleri, Multi-cancer early detection (MCED).
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