A blood test so sensitive that it can spot a single cancer cell lurking among a billion healthy ones has taken a big step closer.
The Boston scientists who invented the test and health care giant Johnson and Johnson will announce that they are joining forces to bring it to market. Four big cancer centres will also start studies using the experimental test this year.
Stray cancer cells in the blood mean that a tumour has spread or is likely to, many doctors believe. A test that can capture such cells has the potential to transform care for many types of cancer, especially breast, prostate, colon and lung.
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, chief of 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, lung cancer chief at 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.
Many people have their cancers diagnosed through needle biopsies, which often do not provide enough of a sample to determine what genes or pathways control a tumour's growth, or the sample may no longer be available by the time the patient sees a specialist to decide what treatment to prescribe.
Doctors typically give a drug or radiation treatment and then do a CT scan two months later to look for tumour shrinkage. Some patients only live long enough to try one or two treatments, so a test that can gauge success sooner, by looking at cancer cells in the blood, could give patients more options.
"If you could find out quickly, 'This drug is working, stay on it', or 'This drug is not working, try something else', that would be huge," Dr Haber said.