Written based on 9 research studies on PubMed, searched on 12 Nov 2026.
The claim
Posts and adverts say that blood tests that look for tumor DNA can find cancer early, sometimes many types at once.
Where research stands
We found 54 published papers on circulating tumor DNA blood test and cancer. They were published between 2021 and 2026. 4 of them are studies in people. At least 178,128 people took part. 3 of them compared people who got it with a group that did not. None was a study in animals, and none was only in cells in the lab. 9 papers are reviews that sum up other studies.
- 4In people3 with a comparison group
- 0In animals
- 0Only in the lab
What the studies found
Trials in people
NHS-Galleri was a randomised trial of a multi-cancer blood test added to usual care, with 142,250 people aged 50 to 77 split into a test group and a control group. [1] The authors report that the main goal, fewer stage III and IV cancer diagnoses in the test group than in the control group, was not met. [1] In the test group, 1.03%, 0.80% and 0.90% of people got a positive result in the three yearly rounds. [1] The authors report that of those positive results, 58.0%, 50.4% and 45.8% turned out to be cancer, and that specificity (correctly clearing people without cancer) was between 99.50% and 99.60%. [1] The test performance results were descriptive, and the authors say no hypothesis testing was done. [1] A second paper describes the design of the NHS-Galleri trial, whose main aim was to see whether the test lowers late-stage cancer diagnoses 3 to 4 years after people join. [2]
Other studies in people
PATHFINDER 2 followed 35,878 people aged 50 or older without suspected cancer, with no control group, and the authors report results as descriptive only. [3] Among 32,007 people whose results could be analysed, the authors report that 0.54% had a cancer found by the test and that 60.3% of positive results were cancer. [3] The authors report that specificity was 99.64% and that sensitivity (the share of cancers the test caught over the follow-up) was 39.3%, so most cancers were not picked up. [3] A modelling study, not a direct test in patients, estimated that a multi-cancer test programme in England could cut late-stage diagnoses and cancer deaths, with larger modelled gains in more deprived groups. [4] A computer simulation of colorectal cancer screening found that multi-cancer blood tests gave about a third to a half of the life-years gained by colonoscopy, so the authors say they are unlikely to replace guideline-recommended screening. [5]
Reviews
A review of 58 studies with 63,309 people found that blood DNA tests for bowel cancer had pooled sensitivity of 82.9% and specificity of 90.7%. [6] A review of three studies in 36,381 average-risk people found pooled sensitivity of 0.72 for invasive bowel cancer, but only 0.13 for advanced pre-cancerous growths. [7] The same review reports that sensitivity rose from 0.53 for stage I to 0.89 for stage IV bowel cancer, so early cancers were missed more often. [7] A review of blood tests that look for many cancers at once looked at test accuracy, harms and mortality in people aged 50 to 79 without suspected cancer. [8] A review of tests for ESR1 gene changes in advanced breast cancer found that different tests vary in how sensitive and specific they are. [9]
Verdict
The one randomised trial of a multi-cancer test (NHS-Galleri, 142,250 people) did not meet its main goal of fewer stage III and IV cancer diagnoses. [1] Reviews of bowel cancer blood tests show early cancers and pre-cancerous growths are missed more often, so the claim is partly true. [7]
Partly true means: people did well, but no fair test with a comparison group has shown it yet. Or only part of the claim holds. How we rate claims
What this means for you: A study in people is not proof that it helps you. Do not stop or change your medicines because of it. Ask your doctor before you start taking it.
Sources
- Performance of a multi-cancer early detection test in the randomized controlled NHS-Galleri trial.2026 · Nat Med · Randomised trial
- Cell-Free DNA-Based Multi-Cancer Early Detection Test in an Asymptomatic Screening Population (NHS-Galleri): Design of a Pragmatic, Prospective Randomised Controlled Trial.2022 · Cancers (Basel) · Randomised trial
- Performance and safety of a multi-cancer early detection test: the PATHFINDER 2 study.2026 · Nat Med · Study in people
- Impact of screening participation on modelled mortality benefits of a multi-cancer early detection test by socioeconomic group in England.2024 · J Epidemiol Community Health · Randomised trial
- Should Multi-Cancer Early Detection Testing Replace Guideline-Recommended Colorectal Cancer Screening? A Comparative Modeling Analysis.2026 · medRxiv · Other paper
- Diagnostic Accuracy of Blood-Based cfDNA/ctDNA Tests for Colorectal Cancer-A Systematic Review and Meta-Analysis.2026 · Cancers (Basel) · Review
- Blood-based circulating tumour DNA (ctDNA) tests for colorectal cancer screening: Systematic review and meta-analysis of diagnostic accuracy.2026 · Crit Rev Oncol Hematol · Review
- Multi-cancer early detection tests for general population screening: a systematic literature review.2025 · Health Technol Assess · Review
- ESR1 ctDNA testing: literature review and comparison of assays for ESR1 mutation detection in advanced hormone receptor-positive breast cancer.2025 · Expert Rev Mol Diagn · Review
