Here Is What the 2026 Science Actually Says
Liquid Biopsy, the Galleri Test, Tumour Markers & What It All Means for You
The Question Millions of People Are Asking
What if a blood test at your annual health check-up could indicate to you if cancer is lurking in your body – before you feel the symptoms? Before the cough turns into a phlegmy cough. Before you feel too weak to get out of bed. Before the X-ray shows a tumour that is Stage III.
It’s not science fiction. By 2026, it will be science fact – and it will be closer to becoming a standard care than you may think. Today, cancer is the number-one cause of death in people aged 50 and older in the US – and the vast majority of cancer deaths are the result of late detection. That’s where the new generation of cancer blood tests – such as the Galleri multi-cancer early detection test, which announced its FDA Premarket Approval application in January 2026 – comes in.
The short answer to the question is yes, but. Yes there are blood tests for cancer and they work, and are getting better. But they aren’t all the same, or all equally accurate, or all equally available. Read more to learn what science tells us, what tests are available, what the Galleri test is and why it’s important, and what you can do about it now.
Breaking — January 2026: FDA Receives Galleri Cancer Blood Test Application
On January 29, 2026, GRAIL submitted the Premarket Approval (PMA) application to the FDA for the Galleri multi-cancer early detection blood test — a test capable of detecting signals from more than 50 cancer types from a single blood draw. The FDA designated it a Breakthrough Device and a 12-month review is now underway. This is the biggest development in cancer screening in a generation.
Table of Contents
Can Cancer Be Detected in a Blood Test? The Honest Answer
It depends – on what blood test you are referring to and what type of cancer you are trying to detect.
Conventional tumour marker blood tests have been around for many years. These test for particular proteins or other substances that are made by cancer cells or by the body in response to cancer. They are useful – but they are not tests for screening people for cancer. Typically they are used to follow up cancer patients to gauge how well treatment is going, or if the cancer has come back.
The game-changing technology of the past five years is a different type of test: multi-cancer early detection (MCED) blood tests (sometimes called liquid biopsy) which can check for signals from tens of different cancers in a single blood test, by looking for genetic material shed by cancer cells into the bloodstream.
By 2026, the science is clear: these tests are effective, they detect cancers missed by other screening and evidence from the world’s largest trials of cancer screening technologies backs their use. Now it’s not a question of whether, but when, these tests will be available and covered by health insurance.
Traditional Blood Tests for Cancer — What Your Doctor Already Uses
To appreciate the new tests, let’s look at current cancer bloods tests:
| Cancer / Test | Blood Marker | Current Role (2026) |
| Prostate | PSA | Screening discussion for men 50+; elevated levels prompt further investigation — not diagnostic alone |
| Ovarian | CA-125 | Monitoring in diagnosed cases; not reliable for population screening — frequently elevated in benign conditions |
| Colorectal | CEA | Treatment monitoring and recurrence detection — not used for initial diagnosis in healthy people |
| Liver (HCC) | AFP | Monitoring in high-risk individuals (cirrhosis, hepatitis B/C) |
| Testicular | AFP, hCG, LDH | Diagnosis, staging, and monitoring — among the most clinically useful tumour markers |
| Blood cancers | CBC, protein electrophoresis | White cell abnormalities, anaemia — often the first indicator of leukaemia, lymphoma, myeloma |
| Pancreatic | CA 19-9 | Monitoring known disease — unreliable for early detection in asymptomatic people |
| Multiple cancers | Galleri (MCED) | Early detection in adults 50+ — screens 50+ cancer types simultaneously from one blood draw |
The main problem with conventional tumour markers is they are specific (i.e. only elevated with cancer) and unsuitable for screening. Prostate-specific antigen (PSA) is raised with benign prostate enlargement. CA-125 is elevated with endometriosis. CEA is raised in smokers. And for other cancers, like pancreatic, ovarian and brain, there are no blood markers at all. Here’s where liquid biopsy comes in.
What Is Liquid Biopsy? The Science Behind the Revolution
Liquid biopsy is the name given by scientists to the technology behind the new blood tests for cancer. It’s beautiful in its simplicity: as cancer cells are born and die, they release their DNA into the blood. These fragments of circulating tumour DNA (ctDNA) have a molecular fingerprint that not only confirms the presence of cancer, but also where it is located.
The game-changing technology is DNA methylation. Methylation is chemical modifications on the DNA that control gene expression. Methylation of cancer cells differs to that of normal cells and these differences are reflected in the cell-free DNA (cfDNA) in your bloodstream. By evaluating these methylation patterns, a liquid biopsy test can not only detect a cancer signal, but also the tissue of origin – where the cancer is likely to be found.
A 2026 review in Biomedicines confirms that emerging liquid biopsy technologies are already moving beyond one-marker tests, to multimodal technologies that combine cell-free DNA signals, circulating tumour cells, extracellular vesicles and RNA markers – alongside artificial intelligence and deep learning – to gain the sensitivity and specificity required for population-level cancer screening.
The bottom line: with a single blood test and computer-based AI analysis, your blood can be screened for cancer signals for 50 or more different cancer types. If there’s a signal, the test also predicts where the origin of the signal is likely to be – so your doctor can recommend the appropriate tests or scans that day.
The Galleri Test — The Most Important Cancer Screening Development in 2026
What Is the Galleri Test?
Galleri is a multi-cancer early detection (MCED) blood test being developed by GRAIL, Inc. It incorporates targeted methylation analysis of cell-free DNA to detect the presence of signals from over 50 types of cancers from one blood sample. The test is meant to be used in adults age 50 or older with no known cancer, and in conjunction with (not in place of) currently recommended screening tests such as mammography and colonoscopy.
The PATHFINDER 2 Study — The Data That Changes Everything
The PATHFINDER 2 study is the largest multi-cancer early detection interventional study ever conducted in the US, with 35,878 participants in the United States and Canada – all of them aged 50 or older, and cancer-free.
The bottom line: the addition of Galleri to all other recommended cancer screenings led to a more than 7x increase in the detection of cancer. Over half of the cancers detected by Galleri were diagnosed at an early stage – when they are most likely to be cured. And perhaps most importantly, 75% of the cancers detected by Galleri have no other recommended screening test – cancers that would never have been detected until they presented with symptoms.
There were no serious adverse events from the study in the 25,000+ participants who had diagnostic work-up following an abnormal result. The test is safe, clinically significant and has the largest amount of data on any MCED test ever.
The NHS-Galleri Trial — 140,000 Participants in England
The NHS-Galleri trial – the first and only randomised controlled trial of a multi-cancer early detection (MCED) test – enrolled over 140,000 healthy adults aged 50 to 77 years old in England. It’s assessing whether the use of Galleri decreases the number of late-stage (Stage III and IV) cancers compared to usual care. Preliminary data will be presented at the American Society of Clinical Oncology (ASCO) annual meeting in May 2026 – the most eagerly awaited clinical results in oncology this year.
Where Things Stand — January 2026
GRAIL filed the last module of the FDA Premarket Approval application for Galleri – based on the PATHFINDER 2 and NHS-Galleri trials – with the FDA on January 29, 2026. The FDA will now review the test for 12 months. The test already has FDA Breakthrough Device Designation. GRAIL has sold about 420,000 commercial Galleri tests as of September 2015 and the test is available now as a laboratory-developed test for about $949, with a doctor’s order.
What These Tests Cannot Do — Honest Limitations
Important: A Negative Result Is Not a Guarantee
A negative MCED test result makes it less likely that the person has cancer, but not impossible. Different cancers and stages are harder to detect. CtDNA is released by the tumour into the bloodstream, and the amount of DNA released depends on the stage of the cancer. These tests should not be used as a substitute for other screening tests or regular visits to the doctor.
- Not equally sensitive to all tumours – the tests are more sensitive to cancers that shed more DNA (later stage) than early-stage cancers
- False positives need work-up – a cancer detected result requires more tests, not a cancer diagnosis; the diagnostic work-up is costly, causes anxiety, and may involve invasive tests
- Not all cancers are detected equally – some cancers, such as those that don’t penetrate the blood-brain barrier (such as some brain tumours), are still difficult to detect
- Accessibility and cost – at a cost of around $949 (without insurance) the Galleri test is not currently affordable by all; equitable access is an important consideration that FDA approval and insurance coverage would address
- Not a replacement for current screening – colonoscopy, mammogram, cervical screening, and low-dose CT for lung cancer are the best available screening tests and should be continued
Who Should Consider a Cancer Blood Test — And What to Do
Galleri is now offered for people over 50 who have not been diagnosed with cancer. It is only available with a doctor’s prescription and is not currently covered by insurance in the US, but will be after FDA approval.
Talk to Your Doctor If You Are:
- 50+ and interested in more cancer screening than the recommended minimum
- At high risk of cancer – family history of cancer, history of cancer, BRCA or other genetic mutations for cancer
- Past or current heavy smoker and want an overall cancer risk assessment
- Someone with a history of cancers that don’t have routine screening tests – pancreatic, ovarian, liver, oesophageal
What Happens If You Test Positive
If you receive a positive result (“cancer signal detected”) from Galleri, it includes a cancer signal origin prediction – where the signal is likely to be coming from. This helps your doctor make the most appropriate diagnostic follow-up: the right scan, the right doctor, the right biopsy if necessary. A positive result doesn’t mean you have cancer, it means there is a signal we need to investigate.
Frequently Asked Questions
Q: Can cancer be detected in a blood test?
Yes. There are two types of blood tests for cancer: older tumour marker tests (PSA, CA-125, CEA and others), which are generally used to monitor patients with known cancers or to test for cancer in high-risk populations; and the new generation of multi-cancer early detection (MCED) blood tests, which use liquid biopsy technology to test for cancer signals from 50 or more different types of cancer. The Galleri test is the most extensively studied MCED test, which has an FDA Premarket Approval application under review since January 2026.
Q: What is the Galleri blood test?
The Galleri test is a multi-cancer early detection (MCED) blood test by GRAIL, Inc. It examines the methylation patterns of cell-free DNA circulating in the blood for cancer signals from over 50 cancers. It’s intended for people 50 years of age and older and is used in conjunction with standard screenings. The PATHFINDER 2 study demonstrated it more than increased cancer detection seven-fold when used in addition to standard recommended screenings, with the majority of cancers detected in early stages.
Q: What is a liquid biopsy?
A liquid biopsy is a blood test that analyses biological material from cancer (particularly, circulating tumour DNA or ctDNA) shed by the cancer cells into the bloodstream. A liquid biopsy is similar to a biopsy (where a sample of tissue is removed from the body) but only a blood sample is needed. Next-generation multi-cancer liquid biopsy tests look at the DNA methylation profile of cell-free DNA to detect cancer and indicate the likely site of the tumour.
Q: Can a normal blood test rule out cancer?
No. A routine blood test (complete blood count or chemistry panel) can’t detect cancer. However, a negative result on an MCED assay, such as Galleri, does not rule out cancer because the sensitivity of detection depends on the type and stage of cancer and very early cancers may not yet have released enough ctDNA into the bloodstream. It is important to continue with regular check-ups, recommended cancer screening tests, and be aware of symptoms.
Q: How accurate is the Galleri cancer blood test?
The Galleri test has a low false-positive rate – in other words, when the test detects a signal that a cancer is present, it’s more likely to be true cancer than a false alarm. The Galleri test found cancers that would have been missed by standard screening tests in the PATHFINDER 2 study of 35,878 people, with around three-quarters of cancers not having another recommended screening test. Different cancers and different stages vary in sensitivity – it’s better at detecting cancers that have progressed.
Conclusion — The Future of Cancer Screening Is in Your Blood
The 2026 science has a definitive and very exciting answer: yes, cancer can be detected by a blood test – we are on the cusp of this becoming mainstream medicine.
Galleri’s FDA Premarket Approval submission (January 2026, based on results from 175,000+ participants in US and UK studies) is a major leap in cancer screening since the invention of the mammogram. It finds three-quarters of cancers for which no other regular screening is recommended. Cancers like pancreatic, ovarian, liver, oesophageal – may be the only way to detect them early.
The technology is not yet fully developed. It is more sensitive at later stages. It’s not a replacement. It’s not 100% accurate. But the trend is clear: a simple annual blood test that will predict 50+ cancers is likely to be as familiar as a blood cholesterol test in the decade ahead.
If you are 50 or older, ask your GP if you are a good candidate for an MCED test. And pass on this article to someone who could benefit from early cancer detection.