Diagnosing sarcoma with a simple blood test? A clinical trial is underway which could be a game-changer.

If you’ve been watching the news this week, you may have heard about a clinical trial for a new blood test, called Galleri, which can detect more than 50 types of cancer before symptoms appear. Is it a game-changer for sarcoma diagnosis? Kate Quillin, Research Officer at Sarcoma UK, digs into the science to find out.

How does the test work?

Both cancer cells and healthy cells leak DNA into the bloodstream, known as cell-free DNA (cfDNA). The Galleri test analyses cfDNA in a blood sample using genetic sequencing technology and artificial intelligence. These tools can pick up patterns of chemical changes that are found in cancer cells, but aren’t found in healthy cells, which allows it to check if a person has cancer.

So far, the technology has only been trialled on people who have already been diagnosed with cancer. The good news is, it worked. The test was able to pick up just over 50% of cases. And it was also able to tell where the cancer is located in the body in nine times out of ten — this is useful for healthcare professionals to choose the right test to confirm a diagnosis.

The Gallieri test analyses cfDNA in a blood sample using genetic sequencing technology and artificial intelligence.

What’s particularly exciting about this blood test is that it promises a safe and accessible way of diagnosing cancer, just requiring a blood sample. The test is also particularly effective at finding cancer types that are considered tricky to diagnose early by current methods — such as head and neck, lung and pancreatic cancers.

Improving early diagnosis of sarcoma

We know that detecting sarcoma early is crucial for improving outcomes for patients. But our National Sarcoma Survey in 2020 found that 30% of sarcoma patients waited more than six months after first consulting with a healthcare professional before they received an accurate diagnosis. The Galleri test could be a game-changer. Sarcomas are among the 50 types of cancer the Galleri test is able to detect, which is promising. But there are a few limitations to iron out along the way. People whose cancers have advanced and spread to other parts of the body have more cfDNA available for the test to detect. This means the technology may not be as reliable in people whose cancers are at an early stage.

What happens next?

Since Galleri has been tested only in people with an existing cancer diagnosis, researchers running the trial are aiming to see if the test can a) detect cancer in people who aren’t suspected of having cancer, and b) find cancers at an earlier stage. If you’ve not been diagnosed with cancer in the last three years and you’re aged between 50 and 77, you might receive a letter from the NHS inviting you to be one of the tens of thousands to take part.

It’ll take another five years or so before the trial is completed and the results are available. Blood tests like Galleri are just one tool in our arsenal to improve the diagnosis and treatment of sarcoma and other cancers.

Dr Sorrel Bickley, Director of Research, Policy and Support at Sarcoma UK said:

‘Many sarcoma patients wait months before they receive an accurate diagnosis, so the development of the Galleri test is a hugely exciting push forward. If this new clinical trial demonstrates that the technology is effective in detecting cancer early, it could truly transform the diagnosis of sarcoma.’

*Research at Sarcoma UK.*