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 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 released by people with cancer.

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.

The findings were published in the journal Science.

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."

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."