Galleri Detects Cancer Signals in 61.6%

The Galleri multi-cancer early detection blood test, which detects tumour-derived DNA fragments and screens for more than 50 cancers, produced promising results in the Pathfinder 2 trial of 23,161 asymptomatic participants. The test returned a “cancer signal” that led to subsequent cancer diagnoses in 61.6% of flagged participants and correctly ruled out cancer in 99.6% of those without disease. It localized the tissue or organ of origin in about 92% of positive cases and identified over half of newly detected cancers at early (stage I–II) stages. Modeling and ESMO-presented analyses suggest adding Galleri to routine screening could increase detections more than sevenfold and detect around 74% of the 12 deadliest cancers. Independent analysis by University of Oxford researchers and Grail indicates about one-third of cases initially labeled “false positives” were later found to have cancer, suggesting the test may detect disease before conventional pathways and could improve diagnostic efficiency. The NHS is running a 140,000-participant trial with possible expansion to about 1 million if results are replicated, but important questions remain about implementation, follow-up pathways, real-world impact and whether MCED testing reduces cancer mortality.