New blood test could detect cancer four years before doctors

A simple blood test could detect cancer up to four years before your doctor does. 

The test called PanSeer correctly identified cancer in 95 percent of asymptomatic people tested by picking up DNA that tumour cells release into the bloodstream, US researchers say.

Research about the test says it looks for chemical changes in the blood and can diagnose five common types of cancer four years before conventional tests. 

New Zealand Cancer Society medical director Dr Chris Jackson says the test is an exciting development.

"Researchers have been trying for quite a long time to pick up cancer at a really early stage and this is what everyone wants," Dr Jackson told The AM Show.

"If you had a choice between a blood test or colonoscopy I'm pretty sure I know what most people will take."

Dr Jackson is hopeful the blood test breakthrough will buy patients valuable time. 

He said it would also benefit those going through treatment.

"We're looking at it in a way for people who have had cancer as a way of picking up early recurrences or looking at whether or not it actually means the treatment's working."

Dr Jackson said still more work needs to be done. 

"This research is exciting but it's also stuff which is being done in New Zealand as well," he said. "This test seems to look at [the] early development of cancer rather than pre-cancerous change at the moment - but, of course, picking up smaller cancers is always going to be better than getting cancers when they're late. You've got a much better chance of curing cancer if you pick it up at an earlier time."

Research about the test was published in the Nature Communications journal.