Galleri is the multi-cancer blood test with the most published evidence behind it. In the guides we publish here, this category is the one where the gap between marketing confidence and published validation is widest, and where the price differences between products track that gap less closely than you would expect.
Four multi-cancer tests are realistically available to a US buyer, and they differ more in what has been demonstrated about them than in what they claim. One single-cancer test outperforms all of them on evidence and covers one disease.
The Verdict
How We Judged Them
Five criteria separate these products, and none of them is the headline sensitivity figure on the front of a brochure.
| Criterion | Why it matters | How the field looks against it |
|---|---|---|
| Published validation in a screening population | A test validated only in people already known to have cancer will look far better than it performs on healthy adults | Galleri and Shield have it. The others rely more heavily on manufacturer data |
| Specificity, and what it means in absolute numbers | At 99.5 percent specificity, 1 in 200 healthy people screened gets a false positive | A test quoting only sensitivity is quoting the flattering half |
| Stage I detection, stated separately | Headline sensitivity averages across all stages and hides poor early detection | Very few products publish this clearly, and it is the number the category is sold on |
| A defined diagnostic pathway after a positive | A positive result is the start of an investigation, and someone has to direct it | Galleri predicts the tissue of origin. A test that cannot say where to look leaves you with a whole-body search |
| An outcome endpoint rather than detection alone | Finding cancer earlier only helps if treating it earlier changes what happens | No product in the category has demonstrated this yet. One trial is running |
The first criterion does most of the separating. A test validated in a case-control design, where the cancer cases are people already diagnosed and the controls are known to be healthy, reports performance that does not survive contact with a screening population. Validation in people whose status was unknown at the time of the draw is a much harder standard, and the field thins out quickly against it.
The Options Compared
Five tests cover the realistic choices, four of them multi-cancer and one included because it beats all of them on evidence within its narrower scope.
| Test | How it works | What it covers | Cost and access | Where it stands on evidence |
|---|---|---|---|---|
| Galleri (GRAIL) | Methylation patterns on circulating tumour DNA | Signal from more than 50 cancer types, with a prediction of where the signal came from | Around $949, prescription required | The largest published dataset in the category, a UK randomised trial with a mortality endpoint, and an FDA advisory committee review scheduled for 23 September 2026 |
| Cancerguard (Exact Sciences) | A combination of DNA methylation, mutation and protein markers | Multiple cancer types, including several with no existing screening programme | Priced below Galleri, prescription required | Launched as a laboratory-developed test rather than through an FDA approval pathway. Less published validation than Galleri |
| Trucheck (Datar Cancer Genetics) | Circulating tumour cell clusters isolated from blood | Multiple solid cancer types, marketed in several countries | Varies widely by market | Company-published performance data. No FDA approval and no independent validation in a US screening population |
| OneTest (20/20 GeneSystems) | A panel of established protein tumour markers read together by an algorithm | A smaller set of cancers than the DNA-based tests | The cheapest option in the category by a wide margin | Built on tumour markers that were never intended for screening healthy people. Treat the algorithm as the claim being made |
| Shield (Guardant Health) | Circulating tumour DNA | Colorectal cancer only | Covered by Medicare at a three-year interval for eligible beneficiaries | The only FDA-approved blood test for primary cancer screening, based on a registrational study of more than 20,000 people |
The evidence column is the one that changes a decision. Galleri and Shield are the two tests whose performance figures come from studies designed to test them in people who did not already know their cancer status.
Galleri Is the Default and Has the Largest Dataset
Galleri reads methylation patterns on circulating tumour DNA and reports two things: whether a cancer signal was detected, and a prediction of which tissue it came from. That second output matters more than it sounds, because it turns a positive result into a directed investigation rather than a whole-body search.
Its published performance sits at roughly 52 percent sensitivity across all stages with 99.5 percent specificity, and GRAIL has been more forthcoming than its competitors about how steeply detection falls at stage I. Our Galleri review works through the pricing, the sign-up process and the detection claims in detail, and our page on cancer screening blood test accuracy covers how to read those two figures against each other.
Two things are moving. An FDA advisory committee review is scheduled for 23 September 2026, which our news brief on the panel covers. Payer access is also widening through employer plans rather than through general coverage, as our brief on Michigan employer plan coverage describes.
Where the Cheaper Tests Sit
Price differences in this category are substantial, and they track the underlying technology rather than a discount on the same product.
Exact Sciences' Cancerguard combines methylation, mutation and protein signals, and came to market as a laboratory-developed test rather than through an FDA pathway. Exact Sciences has the strongest track record in this space through Cologuard, which is a point in its favour. The published validation behind Cancerguard is thinner than Galleri's, and that is the trade being made at the lower price.
Datar Cancer Genetics' Trucheck takes a different approach entirely, isolating circulating tumour cell clusters rather than sequencing DNA fragments. Its published performance comes from company studies, without an FDA approval or independent validation in a US screening population. That does not make the figures wrong. It means nobody outside the company has checked them.
20/20 GeneSystems' OneTest is the cheapest by a wide margin because it reads conventional protein tumour markers, several of which have been available for decades, and applies an algorithm to interpret them together. Those markers were developed for monitoring known cancers rather than screening healthy people, and their individual specificity in a screening context is poor. The claim being sold is the algorithm.
The Single-Cancer Test With the Strongest Evidence
Guardant Health's Shield is not a multi-cancer test and belongs in this comparison anyway, because it is the only blood test the FDA has approved for primary cancer screening.
That approval rests on the ECLIPSE study, which Medicare now recognises for coverage at a three-year interval, and which enrolled more than 20,000 average-risk adults across more than 200 sites and reported about 83 percent sensitivity for colorectal cancer. It is the strongest evidence base attached to any screening blood test currently sold.
Its limitation is equally clear. Shield detects about 13 percent of the advanced precancerous lesions that colonoscopy removes, so it finds colorectal cancer without preventing it. Our comparison of the colon cancer blood test against colonoscopy covers what that gap means for a screening schedule.
What None of Them Have Yet
Three things are missing across the whole category, and they are the same three regardless of which product you buy.
- A mortality result. No multi-cancer test has shown that using it reduces cancer deaths. One trial was designed to find out.
- Strong stage I performance. Detection climbs with stage across every product, which puts the weakest performance exactly where the category's premise requires the strongest.
- A funded diagnostic pathway. The work-up after a positive result is billed separately, coverage varies, and it can cost more than the test. That cost belongs in the decision and rarely appears in the marketing.
Who Should Not Buy One
Four groups get little or nothing from these tests.
- Healthy adults under 45 with no family history. Cancer is rare enough in that group that most positive results will be false alarms, and each one starts a work-up.
- Anyone who would not complete an imaging and biopsy investigation after a positive. A result you will not act on converts an unknown into anxiety and changes nothing else.
- Anyone thinking of it as a replacement for standard screening. Mammography, cervical screening and colonoscopy each outperform a multi-cancer test on their own target disease, and colonoscopy prevents cancer rather than detecting it.
- Anyone with current symptoms. A symptom needs a diagnostic pathway, and a screening test returning a clear result in that situation risks a delay that matters.
Our ranking would change if the NHS-Galleri mortality readout showed no benefit, which would weaken the case for the whole category rather than for one product. It would also change if Exact Sciences published screening-population validation for Cancerguard at a scale comparable to Galleri's, since the price difference is real and the evidence gap is currently what justifies it. Either result would move this page substantially.
Before ordering any multi-cancer blood test, ask your clinician what a positive result would commit you to and whether your age and family history make that result likely to be real.
Frequently Asked Questions
What is the best multi-cancer blood test?
Galleri has the largest published dataset, the clearest reporting of its own limitations, and the only randomised trial in the category with a mortality endpoint. That makes it the default choice for someone who has decided to have a multi-cancer test. It is also the most expensive, and none of that makes it a test everyone should buy. For colorectal cancer specifically, Guardant's Shield is the only FDA-approved blood test for primary screening and has stronger evidence than any multi-cancer product.
How much does a multi-cancer blood test cost?
Galleri is around $949 as a self-pay prescription test, with employer and payer routes appearing in some US markets. Exact Sciences' Cancerguard is priced below it. OneTest is the cheapest option in the category by a wide margin because it reads conventional protein tumour markers rather than sequencing circulating tumour DNA. None of these prices include the diagnostic work-up that follows a positive result, which is billed separately and can exceed the test itself.
Are multi-cancer blood tests covered by insurance?
Generally not as a standard benefit, because no multi-cancer early detection test has FDA approval and Medicare has no benefit category for them. Coverage is appearing through specific employer health plans and self-insured groups rather than through broad payer policy. Guardant's Shield is the exception, and it is a single-cancer test: Medicare covers qualifying blood-based colorectal screening at a three-year interval for eligible beneficiaries.
Do multi-cancer blood tests save lives?
Nobody has shown that yet, and it is the most important open question in the category. Every published figure describes detection rather than outcome, and detecting a cancer earlier only helps if treating it at that point changes survival. The NHS-Galleri trial in the United Kingdom was designed with a mortality endpoint to answer this directly. Until a trial of that kind reports, buying one of these tests is buying earlier information rather than a demonstrated benefit.
Which cancers do these tests find well?
Aggressive cancers that shed material into the bloodstream readily are detected best, and that group includes pancreatic, ovarian and liver cancers. Those are also the cancers with no population screening programme, which is where a multi-cancer test adds something rather than duplicating an existing screen. Detection is poorest for slow-growing, less vascular tumours and for every cancer at stage I, which is the inverse of what an early detection test needs.
Should I get a multi-cancer blood test instead of my usual screening?
No, and every manufacturer says the same. These tests are positioned as additive to guideline screening rather than as a replacement for it. Mammography, cervical screening and colonoscopy each detect their target cancer far more reliably than a multi-cancer blood test does, and colonoscopy prevents cancer outright by removing polyps. A clear multi-cancer result is not a reason to skip any of them.
What is the difference between Galleri and Cancerguard?
Galleri reads methylation patterns on circulating tumour DNA and predicts the tissue of origin. Exact Sciences' Cancerguard combines DNA methylation, mutations and protein markers. The larger practical difference is regulatory and evidential: Galleri has the bigger published dataset and a randomised trial running, while Cancerguard came to market as a laboratory-developed test. Both require a prescription and both position themselves as additive to standard screening.
Is a multi-cancer blood test worth it?
It is worth most to older adults with a family history, and to people at risk of cancers that have no screening programme, because both raise the chance that a positive result is real. It is worth least to healthy adults under 45, where cancer is rare enough that most positives will be false alarms. The deciding question is whether you would complete an imaging and biopsy work-up if the result came back positive. If the answer is no, the test cannot help you.
Related
- Galleri review: the leading option in detail
- Cancer screening blood test accuracy: how to read the figures
- Colon cancer blood test vs colonoscopy: the single-cancer comparison
- Galleri at the FDA advisory panel: what the review changes
- Full body MRI: the imaging route to whole-body screening
- Prenuvo review: the imaging alternative reviewed
- Is Prenuvo worth it: the same decision on the imaging side