Cancer blood test 'great step towards early detection of disease'

A blood test that screens for eight common cancers could change the way doctors screen for the disease, researchers have said.

US scientists have developed a 'liquid biopsy' test, called CancerSEEK, that screens for eight forms of cancer and helps identify its location.

It looks for mutations in 16 genes and evaluates the level of eight proteins usually shed into blood by tumours.

Researchers at John Hopkins University in Maryland tested it on 1,005 patients with cancers of the ovary, liver, stomach, pancreas, esophagus, colorectum, lung or breast.

It correctly detected the disease 70% of the time with a high success rate of 98% for ovarian cancer to a low one of 33% for breast cancer.

A report published in the journal Science said that the test narrowed to one or two places where the cancer might be, such as colon or lung, which is important for limiting the amount of follow-up tests for patients.

It gave only seven false alarms when tried on 812 others without cancer.

Nickolas Papadopoulos, senior author and professor of oncology and pathology, said: "The use of a combination of selected biomarkers for early detection has the potential to change the way we screen for cancer, and it is based on the same rationale for using combinations of drugs to treat cancers."

Bert Vogelstein (right) said the test could identify cancers that go undetected. Credit: APTN

Professor of oncology, Bert Vogelstein said that although the test does not spot every cancer, it identifies many that would likely otherwise go undetected.

He said it could be a great step towards early detection of the disease and ultimately save lives.

"Many of the most promising cancer treatments we have today only benefit a small minority of cancer patients, and we consider them major breakthroughs. If we are going to make progress in early cancer detection, we have to begin looking at it in a more realistic way, recognising that no test will detect all cancers," he said.

"This test represents the next step in changing the focus of cancer research from late-stage disease to early disease, which I believe will be critical to reducing cancer deaths in the long term."

The test is not ready for use yet and needs to be validated in a larger study already underway in the general population rather than cancer patients.

"We're very, very excited and see this as a first step," said Professor Papadopoulos.

"But we don't want people calling up and asking for the test now, because it's not available."

Credit: PA

HOW THE 'LIQUID BIOPSY' WORKS

  • Tumours are made up of cancer cells that change, reproduce and die over time.

  • These cells can get into the bloodstream.

  • And when cancer cells die, they release DNA and other fragments into the blood.

  • The tests can analyse a blood sample for traces of cancer DNA to see what genes and mutations are most active.

  • It can suggest what treatment might help a patient and could be an essential early warning sign that the cancer is present.

A blood sample under the microscope. Credit: APTN

WHAT ARE THE NEXT STEPS?

  • Hopkins and Geisinger Health System in Pennsylvania have started a study of it in 10,000 people who will be tracked for at least five years.

  • The work was financed by many foundations, the Mayo Clinic, the Howard Hughes Medical Institute and National Institutes of Health grants.

  • Researchers say the test, once validated, could cost around $500 (£360) based on current materials and methods but the ultimate goals is to commercialise it with a private company.