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    Analysis

    Multi-cancer blood tests: what NHS-Galleri showed and the FDA debate

    Multi-cancer early detection (MCED) blood tests such as Galleri look for many cancers at once, including ones with no screening test.[1] The first randomised trial, NHS-Galleri, missed its primary goal of fewer stage III or IV cancers but found fewer stage IV cancers.[2][3] An FDA panel backed approval in September 2026; as of 11 October the FDA had not decided.[4][5]

    Editor reviewedStrict sourcingUpdated AnalysisHealth and medicine, Life sciences, Tech policy
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    A single blood test that screens for dozens of cancers is an appealing idea. Many deadly cancers have no recommended screening test, and Galleri, the most advanced multi-cancer early detection (MCED) test, claims to cover more than 50 types.[1][6] In 2026 the first randomised trial reported its results and the FDA began weighing the first application for an MCED test. This page sets out what was measured, what it means, and the competing views.

    This page is not medical advice. Talk to a clinician before taking any screening test, including an MCED test.

    What the trials measured

    NHS-Galleri randomised 142,250 people aged 50 to 77 in England. Half had up to three annual Galleri tests on top of usual NHS screening; for the other half, blood was stored but not tested. GRAIL funded the trial.[7] Its primary endpoint was the rate of stage III or IV cancer across 12 prespecified cancer types. This did not differ significantly between the groups (incidence rate ratio 1.03, 95% CI 0.92 to 1.14).[2]

    The key secondary endpoint, stage IV cancer, had a rate ratio of 0.86 (95% CI 0.74 to 1.00), a 14% reduction that GRAIL described as nominally significant.[3] GRAIL reported that stage IV diagnoses fell by 9%, 22% and 26% in successive rounds, while stage III diagnoses rose, especially in the first round.[8] Fewer than 1% of participants had trial-related adverse events, and none were serious.[9]

    On test accuracy in NHS-Galleri, specificity was 99.50% to 99.60% per round. Positive predictive value, the share of positive results that turned out to be cancer, fell from 58.0% in round one to 45.8% in round three. Episode sensitivity, the share of cancers diagnosed within a year that the test had flagged, was 26.7% to 37.2% for all cancers and 47.6% to 63.4% for the 12 prespecified types.[10] In the single-arm PATHFINDER 2 study of 32,007 North American adults, positive predictive value was 60.3% and specificity 99.64%. Episode sensitivity was 39.3% for all cancers and 69.8% for the 12-cancer group.[11] The PATHFINDER 2 authors say randomised trials and longer follow-up are needed to establish clinical utility.[12]

    The regulatory picture

    GRAIL filed a premarket approval application with the FDA on 29 January 2026. The FDA had granted Galleri Breakthrough Device status in 2018.[13] The application included PATHFINDER 2 initial results, first-round NHS-Galleri data and a bridging study.[14] On 23 September 2026 an FDA advisory panel voted 7-2, with one abstention, that benefits outweigh risks. It voted unanimously on safety and 6-4 on effectiveness. The FDA is not bound by the vote.[4] As of 11 October 2026 Galleri’s own site said the test had not been cleared or approved by the FDA. It is sold by prescription as a laboratory test, and GRAIL expects an FDA decision in the coming months.[5] GRAIL has sold the test in the US since mid-2021, and as of mid-2026 it was not broadly reimbursed.[15]

    How to read the results

    The core disagreement is over what counts as success. Mortality is the gold standard for screening because finding more cancers earlier does not necessarily mean fewer deaths; slow-growing cancers may never cause harm.[16] NHS-Galleri chose a combined stage III and IV endpoint to get an answer within a few years, and that endpoint was not met.[2] The stage IV result is a secondary endpoint with a confidence interval touching 1.0. It is suggestive rather than conclusive.[3]

    The round-by-round pattern is the strongest argument for optimism. If the stage IV reduction grows with repeated screening, as GRAIL reported, a steady-state programme might do better than the three-year average.[8][17] Against that, sensitivity for all cancers was around a third in NHS-Galleri. A negative result therefore offers limited reassurance, which is why GRAIL says the test is an add-on to standard screening, not a replacement.[10][18]

    Specificity near 99.5% sounds high, but at population scale even a small false-positive rate creates diagnostic work. Critics argue that this would put heavy pressure on already stretched diagnostic services.[10][19]

    What happens next

    Forecast, with uncertainty: an FDA decision on the Galleri PMA is likely within months of the September panel, since GRAIL says one is expected “in the coming months”. Approval is not certain, because the agency is not bound by its advisers.[5][4] Even with approval, approval alone would not show that the test reduces cancer deaths. Longer follow-up of NHS-Galleri, which its authors call warranted, will be the key evidence.[19] Approval also would not by itself place MCED tests in USPSTF guidelines, and the task force had not met for over a year as of September 2026.[20]

    For the test itself, see Galleri. For single-cancer blood and stool tests that are already FDA-approved, see the at-home screening test buyer’s guide. Dated events are in the cancer screening tracker.

    Competing views

    Stage IV reduction is meaningful

    GRAIL and the trial's investigators point to a 14% overall fall in stage IV cancers that deepened to 26% by the third round, a four-fold rise in screen-detected cancers and high specificity. They argue the stage III rise reflects cancers caught earlier.[3][8][21][22]

    Promising, but wait for mortality data

    Some independent experts see an encouraging trend but note that a stage shift is a surrogate. Lead-time bias, overdiagnosis and chance can all explain part of it, and UK screening policy does not yet accept late-stage reduction as proof of benefit.[17][16][12]

    Not ready for population use

    Critics stress that the primary endpoint failed, sensitivity for early-stage cancers is low, and false positives would add scans and biopsies to stretched services. They say the data do not justify population-scale use.[2][19][23]

    Next in the crash course

    Developing in Health

    Questions readers ask

    Did the NHS-Galleri trial work?

    It did not meet its primary endpoint. The rate of stage III or IV cancers across 12 prespecified cancer types did not differ significantly between groups (incidence rate ratio 1.03). A key secondary endpoint, stage IV cancer, was 14% lower (rate ratio 0.86, 95% CI 0.74 to 1.00).[2][3]

    How accurate is the Galleri test?

    In NHS-Galleri, specificity was 99.50% to 99.60% across rounds and positive predictive value was 45.8% to 58.0%. Episode sensitivity was 26.7% to 37.2% for all cancers and 47.6% to 63.4% for 12 prespecified types.[10]

    Is Galleri FDA approved?

    Not as of 11 October 2026. GRAIL applied for approval in January 2026, and an FDA advisory panel voted in its favour on 23 September 2026. The FDA is not bound by the vote.[5][13][4]

    Does a multi-cancer test replace mammograms or colonoscopy?

    No. GRAIL says Galleri should be used in addition to routine screening, and a negative result does not rule out cancer.[18]

    Will we know if these tests save lives?

    Not yet. The NEJM authors say further follow-up is needed, and the UK NSC says late-stage reductions cannot yet replace cancer deaths as the measure of screening benefit.[19][16]

    Sources

    · 23 claims from 12 publishers

    Each numbered claim is a statement we checked against the sources listed with it. Tap a number in the text to see its sources in place.

    1. [1]

      Galleri is a prescription blood test that looks for cancer-specific DNA methylation patterns in cell-free DNA, screens for more than 50 cancer types, and predicts where in the body a cancer signal originated. confirmedas of 2026-10-11

    2. [2]

      NHS-Galleri missed its primary endpoint; the rate of stage III or IV cancer across 12 prespecified cancer types did not differ significantly between groups after three rounds (incidence rate ratio 1.03, 95% CI 0.92 to 1.14). confirmedas of 2026-10-11

    3. [3]

      In NHS-Galleri, the incidence rate ratio for stage IV cancer, a key secondary endpoint, was 0.86 (95% CI 0.74 to 1.00) after three rounds, a 14% reduction that GRAIL described as nominally significant. confirmedas of 2026-10-11

    4. [4]

      On 23 September 2026 an FDA advisory panel voted 7-2 with one abstention that Galleri's benefits outweigh its risks, unanimously on safety, and 6-4 on effectiveness, for screening adults aged 50 and older; the FDA is not bound by the vote. confirmedas of 2026-09-23

    5. [5]

      As of 11 October 2026 Galleri's own site stated that the test has not been cleared or approved by the FDA; it is sold as a laboratory-developed test under CLIA and requires a prescription. confirmedas of 2026-10-11

    6. [6]

      The 2021 USPSTF colorectal recommendation does not include blood (serum) tests, urine tests or capsule endoscopy because of limited evidence. confirmedas of 2026-10-11

    7. [7]

      NHS-Galleri randomised 142,250 people aged 50 to 77 in England (71,122 intervention, 71,128 control) to up to three annual Galleri blood tests on top of usual care or to stored blood; it was funded by GRAIL. confirmedas of 2026-10-11

    8. [8]

      GRAIL reported that stage IV diagnoses of the 12 prespecified cancers fell 9%, 22% and 26% in the first, second and third screening rounds, while stage III diagnoses rose, especially in the first round. confirmedas of 2026-10-11

    9. [9]

      Fewer than 1% of NHS-Galleri participants had trial-related adverse events and none were serious. confirmedas of 2026-10-11

    10. [10]

      Across NHS-Galleri's three rounds, specificity was 99.50% to 99.60%, positive predictive value fell from 58.0% to 45.8%, and episode sensitivity was 26.7% to 37.2% for all cancers and 47.6% to 63.4% for the 12 prespecified types. confirmedas of 2026-10-11

    11. [11]

      In PATHFINDER 2 (32,007 performance-analysable North American participants aged 50 or older), Galleri's cancer detection rate was 0.54%, positive predictive value 60.3%, specificity 99.64%, and episode sensitivity 39.3% for all cancers and 69.8% for 12 prespecified cancers; it was a single-arm study. confirmedas of 2026-10-11

    12. [12]

      The PATHFINDER 2 authors state that randomised trials and longer follow-up are needed to assess the clinical utility of MCED tests. confirmedas of 2026-10-11

    13. [13]

      GRAIL submitted a premarket approval (PMA) application for Galleri to the FDA on 29 January 2026; the FDA had designated Galleri a Breakthrough Device in 2018. confirmedas of 2026-10-11

    14. [14]

      GRAIL's PMA included PATHFINDER 2 initial results and first-round NHS-Galleri performance and safety data, plus a bridging study. confirmedas of 2026-08-06

    15. [15]

      GRAIL launched Galleri in the US in mid-2021; as of mid-2026 it was not broadly reimbursed, and FDA approval was not required to market it. confirmedas of 2026-08-06

    16. [16]

      The UK NSC's position (October 2026) is that surrogate outcomes such as fewer late-stage cancers cannot yet replace cancer-specific deaths as the main measure of screening benefit, because finding more early cancers does not necessarily mean fewer deaths. confirmedas of 2026-10-01

    17. [17]

      Nitzan Rosenfeld (Queen Mary University of London) said the strengthening stage IV reduction in later rounds suggests late-stage reductions might accumulate with longer screening, but that this remains untested and stage-shift endpoints are confounded by lead-time bias. confirmedas of 2026-05-30· interpretation

    18. [18]

      GRAIL says Galleri should be used in addition to routine screening, a negative result does not rule out cancer, a positive result needs diagnostic confirmation, and it is not recommended in pregnancy, at age 21 or younger, or during active cancer treatment. confirmedas of 2026-10-11

    19. [19]

      Richard Houlston of the Institute of Cancer Research said the NHS-Galleri findings were presented far more positively than the overall results justify, and warned that low early-stage sensitivity and false positives would mean extra scans and biopsies and pressure on stretched NHS diagnostic services; the NEJM authors say further follow-up is warranted. confirmedas of 2026-05-30

    20. [20]

      As of September 2026 the USPSTF had not met for more than a year after its meetings were cancelled by HHS Secretary Robert F. Kennedy Jr. confirmedas of 2026-09-17

    21. [21]

      GRAIL reported that adding Galleri to standard screening led to a four-fold increase in screen-detected cancers in NHS-Galleri. confirmedas of 2026-10-11

    22. [22]

      GRAIL reported overall NHS-Galleri figures of 52.0% positive predictive value, 99.55% specificity, 92.5% cancer-signal-origin accuracy, and episode sensitivity of 54.7% for the 12 prespecified cancers and 30.7% across all cancers. confirmedas of 2026-10-11

    23. [23]

      Some senior cancer researchers, including Houlston and NCI Director Anthony Letai (as reported by The Cancer Letter in October 2026), have said the current data do not support population-wide use of MCED tests. reportedas of 2026-10-09· interpretation

    Revision history (1)
    1. Page created.

    Created Oct 11, 2026. Last reviewed by an editor on Oct 11, 2026. Next scheduled review: Nov 11, 2026.

    Cite this page

    "Multi-cancer blood tests: what NHS-Galleri showed and the FDA debate." ContentLora, updated Oct 11, 2026. https://contentlora.com/analysis/multi-cancer-early-detection-debate

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