Grail's $950 Galleri Blood Test Finds More Cancer — But Can't Prove It Saves Lives

Grail's Galleri test, a $950 blood draw that screens for more than 50 cancer types, just completed its largest clinical trial to date — a 140,000-person study of older adults in the UK tracked over three years. The headline result: the test failed to achieve its primary goal of meaningfully reducing late-stage cancer diagnoses. That's a significant stumbling block for a product already on the market and quietly embedded in the wellness routines of health-conscious Americans.

The study's numbers tell a mixed story. Galleri did find an additional 937 cancer cases that standard screening would have missed, and Grail President Joshua Ofman frames that as four times more cancer detected when layered on top of traditional single-cancer screening tools. But 54% of those newly detected cancers were already in Stages 3 or 4 — the harder-to-treat categories the test was specifically designed to catch earlier. Meanwhile, the test missed far more than it found: 2,114 people who got a negative Galleri result were diagnosed with cancer within the following 12 months through conventional methods. That puts the test's sensitivity around 30%, meaning it's leaving roughly two cancers undetected for every one it catches.

The false positive picture is more reassuring. Out of more than 70,000 people tested, only 864 received a cancer signal that couldn't be confirmed with follow-up diagnostics — a false positive rate below 0.5%. Grail's founding CEO Jeff Huber argues even those cases may not be true false positives: prior research suggests about a third of unconfirmed positive signals eventually become confirmed diagnoses, meaning the cancer was real but simply undetectable at the time. His bottom line is blunt — a positive Galleri result should be treated as a serious alarm.

One encouraging signal: early-stage (Stage 1 and 2) cancer detection improved by 16% after three years of annual testing, and for cancers with no existing routine screening — like certain gastrointestinal and pancreatic cancers — the test made a more meaningful dent in early detection. But whether catching those cancers a stage earlier actually translates to longer lives remains unknown. Dr. Scott Ramsey of Fred Hutch Cancer Center points out that the relationship between staging and survival varies wildly by cancer type — a shift from Stage 4 to Stage 3 might be lifesaving for one cancer and clinically irrelevant for another.

The fundamental problem is that no data yet shows Galleri reduces cancer mortality — which is the only metric that ultimately justifies a screening program. The test is available by prescription and through telehealth platforms like Hims & Hers, but it has not received FDA approval. Ramsey, who advises friends to hold off, puts it plainly: he believes tests like Galleri will eventually be standard of care, but right now there is no evidence that taking one reduces your risk of dying from cancer. Grail's own former CEO gets tested every year — but also supplements with full-body MRIs and colonoscopies, suggesting even true believers aren't counting on Galleri alone.