ASCO declined to recommend Grail’s Galleri for cancer screening after reviewing data from the NHS-Galleri randomized trial, which failed to meet its primary endpoint. The guidance decision came as questions persisted about whether the trial’s efficacy bar was set too high and how to interpret the distribution of detected cancer stages over time. Grail argued that even without primary endpoint success, the longer-term findings showed fewer late-stage cancers and more early-stage diagnoses after three years. ASCO’s position rested on the primary endpoint miss, with the organization’s leadership saying the assay should not be included in screening guidelines at this time. The development is expected to affect clinicians and cancer programs that have been offering Galleri through early access mechanisms. The decision raises the evidence threshold for population-level multi-cancer early detection use and signals how professional society guidance may shape payer and guideline pathways.