A blood test could predict how well lung cancer patients will respond to treatment by chemotherapy, according to a study published in the journal, Nature.

Often diagnosed late, lung cancer can be difficult to treat and is the leading cause of cancer death. Researchers at the University of Manchester, in the UK, have discovered that a simple blood test could predict whether lung cancer patients will respond to treatment by chemotherapy.

The scientists analyzed isolated cancer cells that had broken away from the main cancer. They discovered that patterns of genetic faults measured before treatment could effectively determine how patients would respond to chemotherapy.

"By identifying differences in the patterns of genetic faults between patients, we now have a starting point to begin to understand more about how drug resistance develops in patients with this aggressive form of lung cancer," explains lead researcher, Caroline Dive.

The study also explored the genetic changes that occurred in patients who initially responded well to treatment but then relapsed. Modifications within cells were found to be different from those in patients who didn't respond well to chemotherapy from the outset. As a result, the scientists suggest that different mechanisms of drug resistance could have developed.