A blood test sensitive enough to detect a cancerous cell among a billion healthy ones could soon be available, it has been revealed.
US scientists behind the test have teamed up with healthcare giant Johnson & Johnson in a bid to bring it to market.
It is thought the test could revolutionise the way cancers - especially breast, colon and lung - are treated. This is because doctors believe that a test capable of identifying single cancer cells could detect whether a cancer is likely to spread.
The test will also be rolled out in studies by four major cancer centres.
Initially, doctors want to use the test to try to predict what treatments would be best for each patient's tumour and find out quickly if they are working.
"This is like a liquid biopsy" that avoids painful tissue sampling and may give a better way to monitor patients than periodic imaging scans, said Dr Daniel Haber at Massachusetts General Hospital's cancer centre and one of the test's inventors.
Ultimately, the test may offer a way to screen for cancer besides the mammograms, colonoscopies and other less-than-ideal methods used now.
"There's a lot of potential here and that's why there's a lot of excitement," said Dr Mark Kris from the Memorial Sloan-Kettering Cancer Centre in New York. He had no role in developing the test, but Sloan-Kettering is one of the sites that will study it this year.