What happens if your Galleri test is positive
It isn't a diagnosis. Here's what the next few weeks actually look like.
Wondering what this means for you? We can help. Talk to a doctor about health checks.
Most people who have the Galleri test get a no signal detected result. About 1 in 100 don't, and it's worth knowing what happens then before you book, not after.
A positive signal detected result isn't a diagnosis. It means the test has picked up a signal that might be cancer, and it tells us where in the body to look first. Just over half the time it is cancer: 52% in the big NHS trial published in September 2026, 60% in the American PATHFINDER 2 study. So it's worth taking seriously, and there's still a real chance it's nothing.
The next step is further investigation of the area the test points to: often imaging, sometimes a blood test or a camera test. PATHFINDER 2 followed 35,335 people through this stage. 290 had a positive result, 213 of them went on to have at least one invasive test such as a biopsy or an endoscopy, and 9 in 10 of those procedures weren't surgery. By the time the results were analysed nobody had had a serious complication from these tests; GRAIL has since reported one, found after the data were locked. Further tests do carry some risk, and we talk each one through with you first. The NHS trial only counted problems up to the point of referral: 0.52% of the tested group against 0.45% of people whose blood was simply stored, none serious, and mostly a bruise or feeling faint when the blood was taken.
People who did have cancer typically had their answer in about five weeks. For those who didn't it took about ten, because ruling something out often takes more than one look. Those weeks can be an anxious time, and we won't leave you to face them on your own. And if nothing is found, it's natural to wonder whether something was missed. In PATHFINDER 2, four of the 290 people with a positive result were told nothing had been found and were then diagnosed with cancer later that year. So if your tests find nothing, we agree a plan with you: when to look again, and what to come straight back to us about. About half of the false alarms turned up something else worth knowing anyway, like a harmless growth.
If your result is positive, we'll call you personally to explain what it means and what happens next. We'll help you to arrange whatever follow-up tests are recommended as quickly as possible. You'll also be offered a conversation with a specialist nurse from the Galleri programme, and we'll stay in touch with you until you have an answer.
If you've decided Galleri is right for you, we'd be glad to help. We'll see you first and take the time to go through the test with you, and the blood test itself is done at the clinic in Westfield. Whatever the result, we'll be with you through what comes next.
Wondering what this means for you? We can help. Talk to a doctor about health checks.
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