ASCO said it will not recommend Grail’s Galleri test for population cancer screening after reviewing results from the NHS-Galleri trial. The decision follows questions about whether the trial’s primary endpoint set too high a bar for MCED performance and whether evidence should support routine guideline inclusion. Reporting indicated the NHS-Galleri trial failed its primary endpoint and did not show a statistically significant reduction in incidence for the targeted advanced cancer outcomes. While Grail emphasized signals such as fewer stage IV cancers and more stage I and II detections after three years, ASCO leadership pointed to the primary endpoint miss. Julie Gralow, ASCO’s chief medical officer, said the assay should not be included in screening guidelines at this time, even while acknowledging that findings were “encouraging.” The stance reflects a cautious approach to integrating MCED tests into population programs before confirmatory evidence meets guideline thresholds. For biotech developers and health systems, the outcome is a clear signal that MCED makers may need stronger evidence packages—particularly on endpoints aligned with screening value—before broad reimbursement and guideline adoption.