A prospective study published on September 22, 2026, in Nature Medicine tested a single blood draw in 35,878 adults aged 50 and older.
The GRAIL Galleri multicancer early detection test flagged signals from 17 different cancer types, and among the newly diagnosed cancers, 53% were caught at stage 1 or 2.
More than seven in ten of the cancer types found had no routine screening program in the United States.
The trial is called PATHFINDER 2 and was led by researchers at Oregon Health & Science University's Knight Cancer Institute, with Mayo Clinic among the participating institutions.
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It is the largest interventional multicancer early detection study done in North America to date.
The Galleri test looks for tiny fragments of DNA that cancer cells shed into the blood.
When the test picks up a signal, it also predicts where in the body the cancer is most likely coming from.
Blood test catches early-stage tumors before they spread
Out of 287 people whose blood test came back positive, 173 turned out to actually have cancer.
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That gives a positive predictive value of 60.3%, meaning roughly six in ten positive tests were true.
The test's specificity was 99.64%, so only about one in 280 healthy participants got a false alarm.
When the test did point to a location, it named one of the two most likely origins 91.3% of the time.
Among the 151 newly diagnosed primary cancers, 70.9% were still at stage 1, 2 or 3.
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That matters because catching a cancer before it spreads gives treatment its best chance of working.
According to the Nature Medicine, 72.8% of the cancers detected were types that currently have no recommended screening test from the U.S. Preventive Services Task Force, such as pancreatic, ovarian, liver and bile duct cancers.
Layered on top of standard screening for breast, cervical, colorectal and lung cancer, the blood test increased the total number of cancers found 6.5-fold, according to the researchers.
What the test can and cannot do
The Galleri test is designed as an add-on to existing screening, not a replacement.
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It is meant for adults aged 50 and older who have no signs of cancer.
Anyone with symptoms should still see a doctor rather than wait for a screening test.
The study also had clear limits. It was single-arm, with no comparison group, and the researchers say randomized trials are still needed to prove that this kind of screening actually saves lives.
Broader work is already running. A study called REACH is now looking at annual multicancer screening in Medicare patients, and a separate project called INFORM is testing the same approach in people with inherited cancer risk.
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Where the test stands with regulators
Galleri is not yet approved by the U.S. Food and Drug Administration.
On September 23, 2026, an FDA advisory panel voted 7 to 2 with one abstention that the test's benefits outweigh its risks, and 6 to 4 that it is effective.
The vote on safety was unanimous. A final FDA decision on the premarket approval application is expected in the coming months.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.