The article mentions: "...sequencing DNA from blood samples and tumour biopsies, to look for mutations that are found in the tumour but not in the blood."
This is pretty common for most cancer genotyping tests. (Sometimes they compare tumor with saliva or some other "benign" source, but the principle is the same.)
This is pretty common for most cancer genotyping tests. (Sometimes they compare tumor with saliva or some other "benign" source, but the principle is the same.)