The British public health service NHS is starting a study with 140,000 volunteers into the functioning of a test to detect cancer via a blood test. ‘It will be important to keep the participants very well informed.’
The test is developed by the American biotech company Grail, which was recently acquired by the also American billion-dollar company Illumina, the world leader in the development and sale of sequencing machines. These allow the DNA of cancer cells to be mapped down to the smallest detail.
Already available on prescription in the United States, the test looks for small fragments of DNA that tumors secrete into the bloodstream, then isolates and reads them. She investigates, among other things, lung, pancreatic, neck, head and throat cancer.
If you detect a tumor at an early stage, patients have more treatment options and a better chance of survival. If you only have to fight the disease in one place at an early stage, it is more likely to succeed than to wage war in multiple organs.
The NHS wants 140,000 people between the ages of 50 and 77 of different ethnic backgrounds to take part in the study. They must not have received a cancer diagnosis in the past three years.
To find out if the test can help doctors, half are screened with it right away, while the other half of the participants’ blood is saved for a potential test in the future. Anyone showing potential traces of cancer will be referred to a hospital for further testing.
‘Revolution in detection and treatment’
According to NHS chief executive Amanda Pritchard, the test could herald ‘a revolution in cancer detection and treatment’ and play a key role in the NHS’ ambition to detect three-quarters of cancers at an early stage, when they are easier to detect. to be treated.
Experts regard the Grail test as promising because such a blood test is minimally invasive, unlike a biopsy that requires surgery. The test can also detect many cancer types at once and is accurate in locating the tumor.
She reports less than 1 percent false positives, misdiagnosing cancer, and is more than 90 percent accurate in locating the tumor, according to previous results in the renowned journal Annals of Oncology.
But experts also have reservations. For example, the sensitivity – the sensitivity with which sick people can be detected – varies between 40 and 90 percent, depending on the type of tumor and the stage of development. That means missing out on a lot of diagnoses and giving people a false sense of security.
I especially see opportunities with such a cancer screening via a blood test in high-risk groups.
Moreover, early tumor detection is the least successful for the time being. ‘That makes sense, because tumors secrete more DNA as they grow larger and come into contact with the bloodstream more,’ says professor Katleen De Preter, who conducts research into cancer at UGent-CRIG (Cancer Research Institute Ghent). ‘I would therefore not call such a test a potential game changer, although it will probably improve as DNA techniques become more sensitive.’
De Preter has another reservation. ‘The percentage of false positives is less than 1 percent, but in such a large-scale English test you still come across a considerable number of people who unnecessarily frighten you.’
‘It will therefore be especially important to keep the participants very well informed,’ says De Preter. ‘I especially see opportunities with such a cancer screening via a blood test in high-risk groups. Think of people with a high degree of reflux, because it is known that they have a higher chance of developing esophageal cancer.’
The first results of the UK cancer screening trial are expected in 2023. If the test proves successful, it will be rolled out to an additional 1 million Britons in 2024 and 2025.