In a fresh advance for the emerging field of personalized medicine, US researchers have developed a blood test based on the DNA of tumors that could assist implement treatment for individual cancer patients.

In the future, this "genetic fingerprint" could be used to pick out tiny remnants of a tumor, Science Translational Medicine reports.

The researchers speculate that time is near when the technology could be used to spot cancer recurrence prior to when they would be diagnosed by scans.

The research involved the scanning of the DNA of tumors achieved from six patients with breast or colon cancer, looking not for tiny DNA changes, but what they call rearrangements in large sections of the genome of tumor cells.

They found between four and 15 DNA rearrangements in each of the six samples. With the help of blood samples obtained from two of the colorectal cancer patients, they discovered the test was sensitive enough to detect this marker or "fingerprint" DNA that had been shed by tumors into the bloodstream.

Study leader Dr Victor Velculescu, from Johns Hopkins Kimmel Cancer Center in Baltimore, said, "I'm quite optimistic that within five years this approach could be turned into something that's widely applicable”.