Credit: https://commons.wikimedia.org/wiki/User:JHeuser

A new blood test uses DNA to spot early signs of returning cancer. It could mean more effective early treatment, though that’s yet to be confirmed.

The test is based around a simple concept: that cancer’s mutation shows up as defective DNA. In the study, researchers at the Francis Crick Institute in London took samples of tumors removed from patients and recorded the defective DNA and how it differed from the patient’s normal DNA.  They then took blood samples from the patients every three months to see if it showed any signs of the defects.

They found that not only could this detect cancer returning, but that it did so as much as a year earlier than other methods, long before any clinical signs appeared. At this point the tumor could be as little as 0.3 cubic millimeters.

Among the patients in the study, 14 had cancer return, of which 13 cases were caught by the blood test. It doesn’t appear there were any false positives.

Although the tests involved lung cancer, the researchers believe it should work the same way for other cancers. What they don’t yet know is whether their assumption that catching the returning cancer so much earlier will make treatment more effective is indeed the case. That will be the subject of future clinical trials.