The test offers the hope of screening patients during routine check-ups, ending the wait for the results of potentially unpleasant biopsies.
Scientists said it would allow surgeons to remove tumours early – preventing them from spreading.
“Knowing the tumour’s location is critical for effective early detection,” said Professor Kun Zhang, a bio-engineer at California University (UC) in San Diego.
The test can pick up the tell-tale signs of tumours – as well as where in the body it’s growing.
There are currently blood tests which screen for the DNA released by dying tumour cells – which shows promise for detecting cancer in patients.
But one major problem is these don’t indicate where the tumour is in the body.
Experts have discovered a clue in blood which can give a clue as to the whereabouts of the tumour.
When a tumour starts to take over a part of the body it competes with normal cells for nutrients and space – killing them off in the process.
As normal cells die they release their DNA into the bloodstream – and it is this that could identify the affected tissue.
The method screens for a particular DNA signature.
Professor Zhang said: “We made this discovery by accident. Initially, we were taking the conventional approach and just looking for cancer cell signals and trying to find out where they were coming from.
“But we were also seeing signals from other cells and realised if we integrate both sets of signals together we could actually determine the presence or absence of a tumour – and where the tumour is growing.”
Cancer survival is dramatically increased if it is caught early enough.
Experts looked at patterns of liver, intestine, bowel, lung, brain, kidney, pancreas, spleen, stomach and blood cancer to look at the DNA patterns.
They also analysed tumour and blood samples from patients at the UC San Diego Moores Cancer Centre to put together a database of cancer-specific genetic markers.
Professor Zhang and colleagues then screened blood samples from individuals with and without tumours and looked for signals of the cancer markers.
The test analyses a combination of signals before they can confirm a positive match.
Professor Zhang said: “This a proof of concept. To move this research to the clinical stage we need to work with oncologists to further optimise and refine this method.”
He said the method is a ‘promising strategy’ for the early detection of a tumour – as well as for the continuous monitoring of tumour progression and metastasis to multiple organs.
“With more plasma samples from patients at multiple clearly defined cancer stages and from healthy controls it’s possible to further improve the prediction sensitivity and specificity to a level adequate for clinical testing.”
The study was published in Nature Genetics.