A GROUNDBREAKING new test can accurately detect more than 50 types of cancer – before symptoms even show, scientists have revealed.
Experts say the check can also accurately distinguish which tissue the cancer originated.
The test, which could eventually be used in national cancer screening programmes, has a 0.7 per cent false positive rate for cancer detection – meaning that less than one per cent of people would be wrongly identified as having cancer.
As a comparison, about 10 per cent of women are wrongly identified as having breast cancer in national screening programmes.
In a paper, published in the leading cancer journal Annals of Oncology today, researchers say the test was also able to predict the tissue in which the cancer had originated in 96 per cent of samples – and was accurate in 93 per cent.
Early detection
Study senior author Dr Michael Seiden, President of US Oncology, said: “The ability to detect multiple deadly cancer types with a single test that has a very low false-positive rate, and the ability to identify where in the body the cancer is located with high accuracy to help healthcare providers to direct next steps for diagnosis and care.
“Considering the burden of cancer in our society, it is important that we continue to explore the possibility that this test might intercept cancers at an earlier stage and, by extension, potentially reduce deaths from cancers for which screening is either not available or has poor adherence.
“To our knowledge, this is the largest clinical genomics study, in participants with and without cancer, to develop and validate a blood test for early detection of multiple cancers.”
DNA changes
Tumours shed DNA into the blood, contributing to what is known as cell-free DNA.
However, as cell-free DNA can come from other types of cells too, it can be difficult to pinpoint when they come from tumours.
The new blood test analyses chemical changes to the DNA – called ‘methylation’ – which usually control gene expression.
Abnormal methylation patterns and the resulting changes in gene expression can contribute to tumour growth, so these signals in cell-free DNA have the potential to detect and localise cancer.
The blood test targets approximately one million of the 30 million methylation sites in the human genome.
An algorithm was used to predict the presence of cancer and the type of cancer-based on the patterns of methylation in the cell-free DNA shed by tumours.
Dr Seiden added: “Our earlier research showed that the methylation approach outperformed both whole genome and targeted sequencing in the detection of multiple deadly cancer types across all clinical stages, and in identifying the tissue of origin.
“It also allowed us to identify the most informative regions of the genome, which are now targeted by the refined methylation test that is reported in this paper.”
Algorithm analysis
In the study, blood samples from nearly 7,000 participants, either with previously untreated cancer or without cancer entirely, were divided between a training set and a validation set.
The algorithm analysed blood samples from the participants to identify methylation changes, and to classify the samples as cancer or non-cancer, and to identify the tissue of origin.
The researchers found that the algorithm’s performance was consistent in both the training and validation sets, with a false positive rate of 0.7 per cent in the validation set.
In 12 types of cancer that are often the most deadly – including bowel, stomach and lung cancer – the true positive rate was 67.3 per cent.
These 12 cancers account for roughly 63 per cent of cancer deaths each year in the USA and, at present, there is no way of screening for the majority of them before symptoms show.
Dr Seiden said: “These data support the ability of this targeted methylation test to meet what we believe are the fundamental requirements for a multi-cancer early detection blood test that could be used for population-level screening.”
First step
Professor Fabrice André, editor-in-chief of Annals of Oncology, added: “This is a landmark study and a first step toward the development of easy-to-perform screening tools.
“Earlier detection of more than 50 per cent of cancers could save millions of lives every year worldwide and could dramatically reduce morbidity induced by aggressive treatments.”
One of the leading cancer experts in the UK believes that innovative new ways of detecting cancer – like the groundbreaking new test – are sorely needed.
Dr David Crosby, head of early detection at Cancer Research UK, said: “Detecting cancers at their earliest stages when they are less aggressive and more treatable has a huge potential to save lives, and we sorely need tech innovations that can turn this potential into reality.
“Although this test is still at an early stage of development, the initial results are encouraging.
“And if the test can be fine-tuned to be more efficient at catching cancers in their earliest stages, it could become a tool for early detection.
“But more research is needed to improve the test’s ability to catch early cancers and we still need to explore how it might work in a real cancer screening scenario.”
