Who will get a Galleri test
Test and control groups
Trials have to be designed in a particular way to understand how well a new test or treatment works. The best way to learn this is to compare two groups of people: one group that did get the new test or treatment, and another that did not. These are called the “test” and “control” groups.
In the NHS-Galleri trial, half of the people in the trial will be in the test group and half will be in the control group.
People in the test group will have their blood samples tested using the Galleri® test. In this group, a small number of tests are expected to show a cancer signal. Anyone with a cancer signal detected will be contacted about their result. No other results will be shared.
People in the control group will have their blood samples stored. Their samples may be tested in the future. They will not receive any results, not even after the trial is finished. A control group is essential in research like this to provide a comparison with the test group.
During and after the trial, the groups will be compared to see if cancers are found in the test group at an earlier stage than in the control group.
Additional information will be recorded about the kinds of cancer found, types of diagnostic tests and cancer treatments, and how successful the treatments are for those in the test group compared to those in the control group.
Deciding who is in the test and control groups
A computer will randomly choose whether you will be in the test or control group. This will be like the computer flipping a coin: you have a 50:50 chance of being in either group.
You will not be told if you are in the test or the control group.
If people know which group they are in, it might alter the way they behave about their health. This could make the research results less clear or reliable.
Who will get a test result
Most people on the trial will not get a test result. Only people in the test group who have a cancer signal detected will be given their test result.
Receiving a cancer signal detected result
If you are in the test group, you will be told if your blood sample shows a cancer signal.
A cancer signal does not mean you definitely have cancer. It just means that you might have cancer, and you need to have some follow-up tests to check.
A research nurse from the trial team will contact you about your result and arrange a follow-up appointment at an NHS hospital for further tests. Your GP will also be told about your result.
Once the research nurse has arranged your hospital appointment, the hospital team will contact you to discuss the next steps to investigate the cancer signal result. This could include follow-up tests like scans, scopes or further blood tests. Your follow-up tests will be booked as soon as possible, depending on local timelines and availability.
If you have not heard from the hospital within five working days of talking to the research nurse, please contact the trial team to check on the progress of the NHS appointment that was organised for you.
About half the people who have a cancer signal detected will be found to have cancer during the follow-up tests, and the other half will not.
If the Galleri test finds a cancer signal, but no cancer is found by your specialist doctor, please continue to come back for study visits and have blood samples taken at those visits.
No other results will be shared
If you are in the test group and your blood sample shows no cancer signal, you will not be given the result. This is for two reasons:
We are still collecting information on how well the test works in the NHS, so it might give people false reassurance if they were told no cancer signal was detected.
In trials, people often do not know if they are in the test or control group. This is important for getting reliable research results. If you are told your test result, you will know you are part of the test group, which could make the research results less clear or reliable.
If you do not receive a result you may still be at risk of cancer so it is important to continue to attend your usual screening appointments and tell your GP if you notice any symptoms that are new or unusual for you.
It is very important that you keep attending your usual cancer screening appointments when you are invited to do so. You should also make an appointment to talk to your GP if you notice any symptoms that are new or unusual for you.
You will be in the majority of participants in the trial and will receive a thank you letter to confirm that your blood sample has been safely received. This normally takes around 30 days to arrive after you have had your blood taken, but may sometimes take longer if sample-checking processes are delayed for any reason.
The control group samples may be tested with the Galleri test in the future to help the research team understand any differences between what happens to people in the test group and the control group. If you are in the control group you will not receive any results from the trial, not even after the trial is finished. You will be asked if your samples can be stored and tested after the trial to help with other research to improve how well the test works.