A ‘revolutionary’ blood test, capable of detecting more than 50 types of cancer even before obvious signs, is being tested in the NHS.
The trial, which began yesterday, will be the world’s largest study of this unprecedented technology.
The test, called Galerie, measures levels of ctDNA, fragments of genetic code that leak from tumors into the bloodstream.
The NHS plans to recruit 140,000 volunteers to test its ctDNA, with the first results of the study by 2023, before trials are launched for another one million Britons.
So what is involved in this new technology, and will it really transform cancer diagnosis and care? We spoke to experts to find out. . .
The test launched tomorrow will be the world’s largest study of this unprecedented technology
What is ctDNA?
Simply put, ctDNA, or circulating tumor DNA, is DNA from cancer cells that is circulating in the bloodstream.
All around our body, cells are constantly growing, dividing and dying. When they die, they release fragments of DNA into the bloodstream and this is known as cell-free DNA.
When this DNA comes from cancer cells instead of healthy cells, it is known as ctDNA.
How does the test work?
The test looks for ctDNA in a small sample — just 10 milliliters or two teaspoons — of the patient’s blood. Despite its name, it does not ‘read’ or examine DNA to find errors or mutations, instead it looks for small chemical ‘traces’ known as DNA methylation patterns.
Methylation is a chemical change in DNA that can be triggered by a number of factors such as aging, smoking and diet – it can turn genes on and off, and has been linked to cancer.
Cancer cells have different methylation patterns from healthy cells, allowing DNA debris from the tumor to be separated from healthy cells. Real analysis takes only a few days.
However, this is not done in the UK but in laboratories in the US and adding time to shipping means it will take two to four weeks to get results from blood samples given as part of the test.
My mother was diagnosed with cancer too late
Tammy Adeloy, 53, a specialist district nurse practitioner, lives in Peckham, south London, with her husband Emmanuel, 61, pastor of the Church of England. The couple has two children together, Christina, 27, and Emmanuel, 23.
On Monday, my husband and I were holding hands as we sat in an adjacent cubicle and took our blood for a test that could tell us if we had cancer.
I have had many patients with it – and have lost many. My husband is also sitting with members of the congregation who have died or died of cancer. We know that it is a disease that can affect anyone.
And there are many types that don’t cause obvious symptoms until it’s too late. My own mother passed away in 2009 from pancreatic cancer with no clear signs in its early stages. She died within three months of diagnosis.
She was only 66 years old and had just retired – after working hard all her life and raising six children. It was too early.
That’s one reason why when I found out about the trial, I didn’t hesitate to sign up.
The exam was straightforward. I don’t like blood tests – nurses can be scared of needles too – but it was okay. It’s a great thing to do.
Technology and treatments have advanced. If we find a way to detect cancer earlier, many lives can be saved.
Tammy Adeloy, 53, a specialist district nurse practitioner, lives in Peckham, south London, with her husband Emmanuel, 61, pastor of the Church of England. The couple has two children, Christina, 27, and Emmanuel, 23.
Which cancers does it check for?
The manufacturers state that the blood test can check for more than 50 types of cancer (see box below) from two tablespoons of blood.
This is possible because studies of the DNA of thousands of healthy people and those with cancer have shown that not only do chemical traces differ between cancer and healthy cells, but they also vary with the type of cancer, Sir Harpal Kumar it is said. The creator of the test, the European arm of GRAIL and former chief executive of Cancer Research UK.
This means that it should be possible to determine what type of cancer a person has by looking at specific chemical markings in specific locations on the DNA.
Can ctDNA show tumor size?
Large tumors shed more DNA into the bloodstream and such high amounts of ctDNA in the blood can give an indication of how advanced the cancer is.
Importantly, some types of cancer release more ctDNA than others – making them particularly easy to detect with this type of test. Sir Harpal explains: ‘One of the very exciting things about this is that we know that some of the more aggressive cancers, where historically we have recognized them too late, like pancreatic cancer, liver, lung, ovary and head And neck cancer sheds more DNA and that’s why we are able to detect them at an early stage.
‘Survival rates for pancreatic cancer have not improved over the past 40 years because it is so difficult to diagnose and only one in four people live longer than a year,’ says Professor Lawrence Young from the University of Molecular Oncology. survives. Warwick.
‘A test that would allow for early detection of pancreatic cancer, before the cancer begins to spread to other parts of the body, would allow us to use surgery, which would be unreliable.’
Does ctDNA Mean You Have Cancer?
No, the ‘positive predictive value’ of the test is more than 40 percent. This indicates your chance of getting cancer with a positive result – if the result is positive, you have about a one in two chance of getting cancer. Sir Harpal says, “There is no such thing as a perfect test.”
So how accurate is the test?
If you have cancer, a study led by the Mayo Clinic in the US and published this month in the journal Annals of Oncology suggests that the more advanced the cancer,…