A blood test called Galleri, which screens for more than 50 cancers, is being trialled in the NHS. In the Pathfinder 2 study in the United States, a cancer signal detected in blood led to a cancer diagnosis in 61.6% of cases. The test also correctly identified the organ or tissue of origin in 92% of positive results. Galleri is designed to be used annually and looks for DNA shed by cancer cells in the bloodstream, offering early indications before symptoms appear.

Among the study findings, more than half of newly detected cancers were at stage I or II (53.5%), and about 69.3% were at stages I–III. In people without cancer, the test correctly ruled out disease in 99.6% of cases. The results are being presented at the European Society for Medical Oncology (ESMO) Congress in Berlin. Grail’s Sir Harpal Kumar said the results are impressive and could help transform cancer outcomes.

The Pathfinder 2 trial examined real-world use alongside standard screening programmes such as those for breast and bowel cancer. Of 23,161 participants from the US and Canada with no symptoms and at least 12 months of follow-up, Galleri detected a cancer signal in 216 individuals, with cancer diagnosed in 133 of them. This yields a positive predictive value of 61.6%. In 92% of positive cases, the test could pinpoint where the cancer started. NHS is planning a trial to evaluate Galleri in people without symptoms, with results expected in mid next year. If positive, officials say it could enable a faster, more targeted diagnostic pathway and earlier treatment. Experts responded with cautious optimism; some noted the need for data on mortality impact and the potential for false positives, while others welcomed the potential for earlier detection and new screening options.