A new blood test has been shown to identify different cancer types with a high degree of accuracy.

When cancer cells die, they shed their DNA into the blood. Previous diagnostic tests work by identifying the genetic mutations present in the cancer cell DNA. However, this technique is limited in its ability to distinguish where the cancer originates from in the body.

The new test focuses on epigenetic makers in the cancer DNA. Epigenetic markers are chemical modifications to the DNA that change the way it is expressed; acting as ‘on’ and ‘off’ switches for genes. One type of epigenetic marker is a methylation, where methyl (CH3) groups are added to the DNA bases. Abnormal methylation patterns are a key hallmark of cancer, and the tests aimed to be able to identify if a person has cancer by studying the genome regions that display excess methylation in cancerous cells.

The blood test was trialled on 1,530 cancer patients and 2,053 people without cancer. The specificity of the test was 99.4%, meaning only 0.6% of the results incorrectly indicated that cancer was present.

The patients had been diagnosed with a range of different cancer including; multiple myeloma, colorectal, oesophageal, lymphoid leukemia and hormone receptor-negative breast. The blood test could also accurately detect the origin organ of the cancer. In the 97% of tests that returned a tissue of origin result, the test correctly determined the organ of origin 89% of the time.

Blood tests are a cheap and non-invasive diagnosis method, which if effectively implemented into healthcare systems could enable much earlier detection of a range of cancers. The likelihood of patient survival is greatly improved by earlier diagnosis.