A new blood test in development has shown ability to screen for numerous types of cancer with a high degree of accuracy.

The test uses next-generation sequencing technology to probe DNA for tiny chemical tags (methylation) that influence whether genes are active or inactive.

When applied to nearly 3600 blood samples – some from patients with cancer, some from people who had not been diagnosed with cancer at the time of the blood draw – the test successfully picked up a cancer signal from the cancer patient samples, and correctly identified the tissue from where the cancer began (the tissue of origin).

The test’s specificity – its ability to return a positive result only when cancer is actually present – was high, as was its ability to pinpoint the organ or tissue of origin, researchers found.

The new test looks for DNA, which cancer cells shed into the bloodstream when they die.

In contrast to “liquid biopsies,” which detect genetic mutations or other cancer-related alterations in DNA, the technology focuses on modifications to DNA known as methyl groups.

Methyl groups are chemical units that can be attached to DNA, in a process called methylation, to control which genes are “on” and which are “off.” Abnormal patterns of methylation turn out to be, in many cases, more indicative of cancer – and cancer type – than mutations are. The new test zeroes in on portions of the genome where abnormal methylation patterns are found in cancer cells.

The overall specificity was 99.4 per cent, meaning only 0.6 per cent of the results incorrectly indicated that cancer was present.

Detecting even a modest percent of common cancers early could translate into many patients who may be able to receive more effective treatment if the test were in wide use.

Is the potential discovery of cancer by an easy blood test, likely to prevent a lot more people dying from cancer?