Sequencing The Traces of Tumour DNA in Blood

A leader in genetic sequencing is betting that it can detect cancer at its earliest stages on the basis of minuscule amounts of genetic material circulating in a person’s bloodstream. But specialists warn that there are many technical hurdles to such an application.

Illumina, a leader in genetic sequencing has recently announced that it has formed a venture that will use genetic-sequencing technology to detect cancer through a simple blood test. Based on biomarkers detection, this technology will identify tumour-specific DNA or RNA in the blood before a person has begun to show symptoms. Blood testThe venture called GRAIL received a total of US $100 million in funding, among the investors are also Bill Gates and Jeff Bezos’s investment firm. The fact that large companies are getting involved is encouraging but there will still be a tremendous effort needed to overcome some of the barriers of non-invasive detection methods. For example, since only around 0.01% of circulating DNA in a person with asymptomatic cancer might come from a tumour it is difficult to guarantee extremely sensitive detection, without generating an unacceptable number of false positives. The recent study in which a blood test was used to detect lung cancer successfully identified 70% of the lung cancer cases, but there was still 30% of false negatives. It is also not clear how much information free-floating DNA can give about a tumour’s location in the body.

Illumina estimates that the market for a cancer-screening test performed once a year on healthy adults could be worth $20 billion to $100 billion.

However, since non-invasive prenatal screening has been a huge success it is a matter of time, when this can be expected in cancer diagnostics as well. The global market for non-invasive prenatal screening is estimated to be more than $500 million, and it is growing rapidly. Illumina estimates that the market for a cancer-screening test performed once a year on healthy adults could be worth $20 billion to $100 billion, depending on how well it works. The company aims to market a test by 2019 that would check for many types of tumours. But in order to reach that goal they would require a number of technical advances.

In the past four years, researchers have demonstrated that tumour DNA circulating in the blood can be detected through genetic sequencing (1); that such DNA has different characteristics from normal DNA, which may make it easier to detect (2) and that it may be possible to use this circulating DNA to pinpoint the location of a tumour (3). Yet it remains to be seen whether those advances and others can be incorporated into a test that provides useful information to apparently healthy people and to their physicians.


By Jana Erjavec, PhD, BioSistemika LLC


Original article: Nature News

Featured image courtesy:  Scott Tysick (Getty Images)

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