All-cause mortality as the primary endpoint for the GRAIL/National Health Service England multi-cancer screening trial.

A randomized trial of the GRAIL GalleriTM multi-cancer screening test is being planned for the National Health Service in England, and will have 140,000 healthy participants aged 50-79: 70,000 exposed to screening and 70,000 unexposed. The test reportedly detects 50 different cancers and is expected to reduce all-cancer mortality by approximately 25%. Given this effect size-and that cancer deaths constitute a large fraction of all deaths-the trial is sufficiently large to test the effect on all-cause mortality. Because most patients believe cancer screening "saves lives", the GRAIL/National Health Service collaboration could set the evaluation standard for multi-cancer screening.