You may have seen in the news that NHS England has decided to wait for the final results of the ongoing NHS-Galleri trial before considering whether an NHS rollout of the multi cancer early detection blood test (MCBT) should go ahead. The trial started in 2023, and the final results are expected in 2026.
So, what is the NHS-Galleri trial and how does it affect the brain tumour community?
The NHS-Galleri trial is a three-year programme designed to assess the effectiveness of a blood test that can detect 50 cancer types before symptoms arise – the multi cancer early detection blood test (MCBT). The idea is to catch cancers at an early stage (stage 1 and 2) which increases the treatment options available to patients and is known to improve survival outcomes.
The MCBT works by looking for DNA found in the blood that’s shed by both tumour cells and healthy cells into the bloodstream. This type of DNA is called cell-free DNA (cfDNA). It then uses modern genetic sequencing technology and artificial intelligence to scan for cancer signals in the cfDNA that aren’t found in healthy cells. The signal is then examined to predict where in the body the cancer signal is coming from.
There are more than 50 different cancer types included in the NHS-Galleri trial, but brain tumours are not included among them. Why is this?
At present, there are 21 possible cancer signals that can be identified from the Galleri test. However, brain tumour signals are not included in them. The researcher’s original work used to validate the test across 50 different cancer types also did not include an analysis on brain tumours. Why?
The brain is protected from external infiltrators by the blood brain barrier, this not only stops things from getting into the brain but may also stop things from leaving. This could make cfDNA shed from brain tumours very difficult to detect as it may be less likely to get into the main bloodstream. Equally, it is feasible that more research needs to be done to understand if it is possible to diagnose brain cancer from blood tests; work on this is currently being undertaken at our Centre of Excellence at Imperial College London.
As the technology develops, so may its sensitivity and thus its ability to detect cfDNA in very low concentrations. Therefore, we will be following the NHS-Galleri trial and technology as it develops very closely.
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