New blood test could ‘transform’ cancer diagnosis

A new type of test can detect genetic mutations in minute amounts of DNA released from cancer cells into the blood, according to a report in the Journal of Molecular Diagnostics.

The test, which is called single colour digital PCR, requires only a fraction of a tube of blood and can detect defects in a sample as small as three molecules. According to the report, the test could be adapted to recognise mutations unique to any individual cancer.

The study’s lead investigator, Hanlee Ji, MD, said: ‘For monitoring patient tumours, only a handful of blood tests are available which are limited to only several types of cancers. Nearly all cancer patients require monitoring by whole body imaging, which can be costly, complex, and time-consuming. In contrast, molecular tests like the one we have developed will enable patients to be monitored at every visit, and thus have the potential for quickly tracking cancer growth and spread.’

‘Moreover, the test’s rapid turnaround and relatively low cost, especially compared to next-generation DNA sequencing, provide a potential opportunity for universal monitoring of more patients than is currently done.’

During trials, the researchers analysed samples from six patients, five of whom had previously been diagnosed with colorectal cancer and one with cholangiocarcinoma.

They were able to identify tumour-derived circulating DNA from three of them. In one patient, the assay was able to show the presence of three different mutations. The three patients, whose samples did not show elevated cancer DNA, were undergoing active treatment at the time of collection.
The developers say the new test offers several advantages over other methods of tumour DNA analysis. The main advantage is that the new technique does not rely on pre-amplification – the repeated copying of a piece of DNA – which can introduce errors and biases.
The study’s lead author, Christina Wood Bouwens, said: ‘This test is simple enough to set up and analyse without extensive training, and therefore, it can be implemented by anyone, making it highly accessible to any laboratory. It has been truly motivating to work with a technology that will help transform the way that we monitor and treat individuals with cancer. I am excited to share our findings with the cancer research community.’