PATHFINDER 2 finds a cancer signal in 0.54 per cent of adults over 50
The PATHFINDER 2 study found a multi-cancer blood signal in 0.54 per cent of 32,007 adults aged 50 or older with no clinical suspicion of cancer. Cancer was present in 60.3 per cent of positives, and specificity was 99.64 per cent. OHSU, where investigator Nima Nabavizadeh works, says adding the test raised detection 6.5-fold and that 173 people with a positive signal were diagnosed with cancer.
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How often the signal appeared
The peer-reviewed PATHFINDER 2 study found a blood multi-cancer signal in 0.54 per cent of 32,007 adults aged 50 or older who had no clinical suspicion of cancer. Cancer was present in 60.3 per cent of positives, while episode sensitivity across all cancers was 39.3 per cent. Between December 2021 and July 2024, 35,878 people enrolled. OHSU reports that the findings were published in Nature Medicine and that, of people with a positive signal, 173 were diagnosed with cancer, which it presents as a positive predictive value of 60.3 per cent. Specificity on both accounts is 99.64 per cent.[1], [2]
What the study did not measure
Specificity was 99.64 per cent. Episode sensitivity in a prespecified group of 12 cancers was 69.8 per cent. The number needed to screen to detect one cancer was 185. Endpoints were descriptive: the study did not test a hypothesis and did not measure a survival gain. OHSU's 6.5-fold claim is a different sentence from those endpoints. The university says adding the blood test helped increase cancer detection 6.5-fold and names Nima Nabavizadeh as principal investigator. That fold is OHSU's account of adding the Galleri test to routine screening, not a figure the Nature Medicine abstract substitutes for the 185 or the 39.3 per cent.[1], [2]
Two ways to say what a positive means
A positive in this study was uncommon, 0.54 per cent of 32,007 people, and 60.3 per cent of those positives were cancer. OHSU's 173 diagnoses are that positive group counted as people, paired with the same 60.3 per cent and the same 99.64 per cent specificity. Sensitivity across all cancers, 39.3 per cent, and sensitivity in the prespecified 12 cancers, 69.8 per cent, remain the paper's figures. The 6.5-fold line is the university's claim about routine screening. Neither page reports a survival gain.[1], [2]
