The crucial signature was linked to a gene called ZNF154. Researchers found that when a tumour was present, the gene showed increased signs of 'methylation' – a biological process which tells genes to switch to the 'off' position.
"Finding a distinctive methylation-based signature is like looking for a spruce tree in a pine forest," said Dr Laura Elnitski, a computational biologist in the Intramural Research Program at National Human Genome Research Institute (NHGRI).
"It's a technical challenge to identify, but we found an elevated methylation signature around the gene known as ZNF154 that is unique to tumours."
Preparing for a mammography Currently women are forced to take mamograms to check for breast cancer ALAMY
Current blood tests are specific to a known tumour type and doctors must first find the cancer, remove a sample of it and determine its genetic sequence.
Once the tumor-specific mutations are known, they can then be tracked for appearance in the blood.
But the new test does not need any prior knowledge of the cancer and would be far less invasive than other screening approaches such as colonoscopies and mammograms. It could also be used to monitor people who are at high risk for cancer or to keep an eye on the activity of a tumour during treatment.