An international team of scientists have developed a blood test, – the Galleri test – that screens for more than 50 different cancers in older people and can detect many at an early stage.
The test is sensitive to cancer DNA floating freely in the blood and cancer-related proteins. Machine learning has enabled the test to look for multiple cancer types and predict their origin with a high degree of accuracy.
The test was able to detect tumours in 70 per cent of patients on average; 17 per cent of cancers at a very early stage, 40 per cent at stage 2, 77 per cent at stage three and over 90 per cent at stage four.
Early detection is the gold standard for cancer treatment. Not only does it increase the survival rate by five to 10 times, it also reduces the complexity and cost of treatment.
At present screening is available for only five cancer types: breast, colorectal, cervical, lung and prostate. These together make up less than half of cancers usually found in people over 50. They also result in high rates of false positives, leading to unnecessary treatments.
Two Australians, Professor Peter Gibbs and Associate Professor Jeanne Tie of the Walter and Eliza Hall Institute, were involved in developing the test.
Professor Gibbs said blood tests that could accurately detect the early stages of cancer, well before symptoms are present, were urgently needed as cancer mortality rates are directly related to how advanced a cancer is at diagnosis.
“While screening tests for some cancers have already been developed, and are associated with earlier diagnosis and better outcomes, for many major tumour types there are no effective screening tests.
Significantly existing tests can only screen for one cancer at a time,” he said.
The Galleri test can positively detect between 69 and 98 per cent of people who had cancer of the ovary, liver, stomach, pancreas, and oesophagus, for which no screening tests are currently available.
The specificity of Galleri was greater than 99 per cent, meaning that fewer than one per cent of people had a false positive result from the test.
Associate Professor Tie said the Galleri test had the potential to be a one-stop, safe screening test for multiple tumour types that should have high community acceptance.
“For the first time we have the promise of a screening test that will lead to earlier diagnosis and improved survival outcomes for many tumour types that are major contributors to cancer deaths in our community,” she said.
Professor Gibbs said he hopes the test would become part of a regular check-up at least once a year.
“It’s probably going to have a much bigger impact on tumours like pancreas cancer which are almost always diagnosed late, rather than bowel cancer which we pick up a little bit earlier,” he said.
“It is going to vary cancer by cancer, but it should have a major impact on all the tumour types and reduce cancer deaths in Australia by many thousands,” he said.
While the test is already in use in the United States, the Oxford University in Britain is looking for 100,000 volunteers from a range of ethnic backgrounds to provide blood sample to assess how well the test works in the UK system.
Those taking part will be advised to carry on with their usual screening appointments and contact their GP if they notice any new or unusual symptoms. The small minority who are found to have potential signs of cancer in their blood will be referred to a hospital for further tests.
Professor Crispin Dass of Curtin University medical school said the test has potential in Australia where the incidence of cancers is quite high.
“However, I think we should wait for the results of the Oxford University study and not jump right in. They should be available in one or two years.”
The test is available in the US at a cost of around $1200.
“The cost is important, while it may come down with widespread use it is not certain if it would be cost effective at this stage,” he said.