A simple blood test that can detect cancer before a tumor has taken shape has been developed by British and American scientists, The London Times reported Tuesday.

The test is the first to identify accurately the signals sent out by a person’s immune system as a cancer germinates. Research suggests that such signals can be detected up to five years before a tumor is spotted, priming doctors to intervene at the earliest moment when a solid cancer appears.

“We are starting to understand carcinogenesis in a way that we have never seen before — seeing which proteins are going wrong, and how the immune system responds. It’s as if your body is shouting ‘I’ve got cancer’ way before a tumor can be detected,” said Professor John Robertson, a breast cancer specialist who led the research.

British scientists described the test, devised initially for lung cancer, as a means of tackling the U.K.’s poor record of early diagnosis and disease survival. Detection of lung, pancreas and throat cancers is often so late that it acts as little more than confirmation of imminent death.

The test, which costs $433, has been piloted in the U.S. and is due to be introduced in Britain next year.

Click here to read more from The London Times.