Multi-cancer early detection (MCED) blood tests continue to face clinical validation challenges after Grail’s Galleri test failed to meet its primary endpoint in the large NHS-Galleri trial. The three-year study, which screened over 142,000 asymptomatic participants aged 50–77, did not demonstrate a statistically significant reduction in late-stage (III–IV) cancer diagnoses compared to standard screening alone—triggering a sharp decline in the company’s share value.
While secondary analyses showed a favorable trend toward fewer late-stage cancers and a meaningful reduction in stage IV diagnoses in certain cancer subgroups, the trial outcome raises fresh concerns around the real-world utility of MCED tests for population-level screening. With no FDA-approved multi-cancer screening tests currently available, analysts suggest the results could complicate Galleri’s regulatory approval pathway and future Medicare coverage prospects despite continued commercial availability as a laboratory-developed test in the U.S.