Description
Galleri Cancer Test – Multi-Cancer Early Detection from a Single Blood Sample
The Galleri Cancer Test is an advanced multi-cancer early detection (MCED) blood test designed to look for a cancer-associated signal across more than 50 types of cancer from a single blood sample.
Unlike conventional cancer screening, which usually looks for one particular type of cancer at a time, Galleri can screen for signals associated with many different cancers simultaneously – including a number of cancers for which there is currently no routine population screening programme.
Galleri is intended to be used alongside established cancer screening, not instead of it. It does not detect every cancer and false-positive and false-negative results can occur.
How Does the Galleri Cancer Test Work?
Cells naturally release small fragments of DNA into the bloodstream. These fragments are known as cell-free DNA (cfDNA). Cancer cells can also release DNA into the blood.
Galleri analyses patterns of chemical modification known as DNA methylation. These methylation patterns act like molecular fingerprints and can help identify DNA associated with cancer.
If Galleri detects a cancer-associated signal, it also predicts the Cancer Signal Origin – the tissue or organ from which the signal is most likely to have originated. This can help guide the next stage of diagnostic investigation.
Watch: How Does the Galleri Test Work?
What Cancers Can Galleri Screen For?
Galleri screens for a signal shared by more than 50 different cancer types. These include a range of cancers for which established population screening programmes do not currently exist.
The cancers diagnosed after a Cancer Signal Detected result in clinical studies have included cancers of the bowel, pancreas, ovary, lung, stomach, oesophagus, head and neck, liver, gallbladder, bladder, kidney, breast and cervix, as well as lymphoma, myeloma and other malignancies.
However, Galleri does not detect every cancer. Its ability to detect a cancer signal varies according to the type and stage of cancer, and not all cancers shed detectable amounts of DNA into the bloodstream.
Who Should Consider the Galleri Cancer Test?
Galleri is recommended for adults with an elevated risk of cancer, such as people aged 50 years or over. Cancer risk rises significantly with age, although other factors such as smoking history, personal medical history and family history may also influence an individual’s risk.
Galleri may particularly appeal to people who want to extend cancer screening beyond the limited number of cancers for which routine screening programmes currently exist.
Galleri is not recommended for people who are pregnant, aged 21 years or younger, or undergoing active cancer treatment.
At Innermost Healthcare, Galleri is provided within a consultant-led cancer testing service, allowing the appropriateness, benefits and limitations of testing to be considered in the context of your individual circumstances.
What Result Will I Receive?
There are two principal Galleri results:
No Cancer Signal Detected
No cancer-associated signal has been identified in the blood sample.
This is reassuring, but it does not mean that cancer can be completely excluded. Galleri cannot detect every cancer and false-negative results can occur.
You should continue to attend any routine cancer screening recommended for you and seek medical assessment if you develop concerning symptoms.
Cancer Signal Detected
A signal associated with cancer has been identified.
The Galleri report will also provide a predicted Cancer Signal Origin, indicating the tissue or organ from which the signal is most likely to have originated.
A Cancer Signal Detected result does not itself diagnose cancer. Further diagnostic investigation is required to determine whether cancer is actually present.
Depending on the predicted Cancer Signal Origin, further investigation might include CT, MRI or ultrasound imaging, endoscopy, specialist consultation, biopsy or other appropriate diagnostic tests.
How Accurate Is the Galleri Cancer Test?
One of the important features of Galleri is its low false-positive rate.
In current Galleri clinical data, the false-positive rate in people without cancer is approximately 0.4%. This means that approximately 1 in 250 people without cancer might be expected to receive a false-positive Cancer Signal Detected result.
Among people receiving a Cancer Signal Detected result in current Galleri clinical data, approximately 62% were subsequently confirmed to have cancer following diagnostic investigation.
These figures describe performance in the populations studied and cannot predict the outcome for an individual patient. Galleri’s sensitivity also varies according to cancer type and stage.
What Does a Negative Galleri Result Mean?
A No Cancer Signal Detected result should not be interpreted as meaning that you definitely do not have cancer.
Galleri does not detect all cancers and some cancers may not shed sufficient DNA into the bloodstream to produce a detectable signal.
If you have symptoms that could indicate cancer, appropriate medical assessment should therefore take priority regardless of the Galleri result.
Does Galleri Replace NHS Cancer Screening?
No.
Galleri is intended to complement rather than replace established cancer screening programmes.
You should continue to participate in NHS or other recommended screening programmes for which you are eligible, including appropriate breast, cervical, bowel and lung cancer screening.
Galleri provides an additional opportunity to screen for signals associated with numerous cancers, including many for which routine population screening is not currently available.
What Has the NHS-Galleri Trial Shown?
The NHS-Galleri trial is one of the largest studies ever undertaken of a multi-cancer early detection blood test. More than 142,000 volunteers aged 50–77 across England participated and underwent repeated annual screening.
The first full results were presented in 2026. The trial did not demonstrate a statistically significant overall reduction in combined stage III and stage IV cancers, which was an important primary outcome.
However, fewer of the most advanced stage IV cancers were diagnosed in the group offered annual Galleri testing, and the study provides important large-scale evidence about how multi-cancer blood testing performs when added to conventional cancer screening.
Galleri therefore remains an additional screening tool rather than a replacement for established screening or diagnostic investigation.
Is Galleri a Hereditary Cancer Genetic Test?
No.
Galleri is designed to look for signals that may indicate the presence of cancer at the time of testing.
It does not determine whether you have inherited a genetic variant associated with an increased future risk of developing cancer.
Hereditary cancer genetic tests instead look for inherited variants such as BRCA1, BRCA2 and genes associated with Lynch syndrome.
If your principal concern is a strong personal or family history of cancer, our Hereditary Cancer Genetic Testing service may be more appropriate or may sometimes be considered alongside other testing.
What If I Already Have Cancer?
Galleri is principally a cancer screening test. It is not intended for patients undergoing active cancer treatment and is not designed primarily to monitor treatment response or cancer recurrence.
If you have already been diagnosed with cancer, are currently undergoing treatment or require surveillance following treatment, our CancerTrack Cancer Monitoring Test may be more appropriate.
CancerTrack is designed to analyse tumour-derived material in the blood over time and may provide additional information about treatment response, molecular changes or possible recurrence.
What If I Have Symptoms?
Galleri should not be used as a substitute for investigating symptoms that could potentially indicate cancer.
If you have symptoms such as an unexplained lump, abnormal bleeding, persistent change in bowel habit, unexplained weight loss, persistent pain or another concerning symptom, you should seek appropriate medical assessment even if a Galleri result is negative.
Patient Experiences with the Galleri Test
Hear from people who have undergone Galleri multi-cancer early detection testing and learn more about their experiences.
Galleri Testing at Innermost Healthcare
Innermost Healthcare provides the Galleri Cancer Test as part of our consultant-led private cancer testing service.
We can discuss whether Galleri is appropriate for you, arrange collection of your blood sample and provide clinical guidance regarding your result and any further investigation that may be required.
Innermost Healthcare is a Healthcare Inspectorate Wales registered, consultant-led healthcare provider with established experience providing advanced genomic and cancer-related testing.
One blood sample. More than 50 cancer types screened. Consultant-led care.
Frequently Asked Questions
Can Galleri detect all cancers?
No. Galleri screens for a signal shared by more than 50 cancer types, but it does not detect every cancer and false-negative results can occur.
Does a Cancer Signal Detected result mean I definitely have cancer?
No. A Cancer Signal Detected result requires further diagnostic investigation before cancer can be confirmed or excluded.
Does a negative Galleri result mean I definitely do not have cancer?
No. A No Cancer Signal Detected result cannot completely exclude cancer.
Should I continue normal cancer screening after Galleri?
Yes. Galleri should be used in addition to established screening programmes recommended for you.
Is Galleri suitable if I have symptoms?
Galleri is a screening test rather than a diagnostic test. Symptoms that could indicate cancer should be medically assessed regardless of whether you have undergone Galleri testing.
Is Galleri the same as a BRCA or hereditary cancer test?
No. Galleri looks for a signal that may indicate cancer is present now. Hereditary cancer genetic testing looks for inherited variants that may increase your future lifetime risk of developing cancer.
Important Information
The Galleri Cancer Test does not detect all cancers. False-positive and false-negative results can occur.
A Cancer Signal Detected result requires further diagnostic investigation and does not constitute a diagnosis of cancer.
A No Cancer Signal Detected result does not exclude cancer.
Galleri should be used in addition to, rather than instead of, established cancer screening programmes and should not delay appropriate medical investigation of symptoms.
Innermost Healthcare