The blood test that could spot early signs of cancer

It looks for tell-tale signs in the blood long before symptoms appear and could save thousands of lives every year.

In tests, researchers say they have spotted early signs of breast cancer in women.

They believe vital clues to other killer diseases will follow.

Doctors believe blood tests will revolutionise cancer prevention by offering cheaper and less invasive screening techniques.

Accurate and timely diagnosis can make the difference between life and death - particularly with breast and bowel cancer.

Most people, however, go to their doctors only once symptoms have appeared.

The Southampton University research team is looking at blood samples collected by a GP from 11,000 Guernsey women over the last 30 years.

Some of the women later developed-cancer, making their records especially valuable.

The researchers looked for "biomarkers" - proteins produced by cancer cells.

Paul Townsend, who is leading the study, said: "Already we have seen significant bio-markers of breast cancer in the samples.

"The quality of the samples we have from Guernsey has been the key but it is early days."

Explaining the thinking behind the research, he added: "Some of the ladies in the samples were healthy at the time but then went on to develop cancer.

"We are going back through these time capsules to look for things common in their blood that we can identify as a cancer fingerprint.

"We are trying to find out if we can take a sample from someone that is healthy and see if they could get cancer in the future.

"We would like to establish a set of rules that we could look for.

"It is early days in terms of our research but it's looking very encouraging at the moment.

"There's a lot more work to be done but I'm hopeful we could have something in terms of a basic theory quite soon."

An all-purpose cancer blood test could be quicker, cheaper, more accurate and less invasive than other tests.

Breast cancer screening, for example, is offered only every three years.

Earlier diagnosis could add to the 1,400 lives thought to be saved every year by the existing programme.

The test could also replace Health Service screening for cervical cancer.

A blood test could improve the uptake of the bowel cancer screening programme, which is being rolled out across Britain.

Although the disease kills 16,000 a year, many patients are squeamish about collecting stool samples and sending them off for laboratory analysis.

A blood test for bowel cancer could dramatically increase the numbers prepared to be screened.

Dr Townsend said that the blood test could be available within ten years if the project receives enough "money and effort".

"Cancer diagnosis is certainly the holy grail," he said. "This is definitely a step in the right direction. If we could spot the signs early we could give the patient the treatment they need."

More than 150,000 Britons die from cancer each year.

Lung cancer is by far the biggest killer - with more than 30,000 deaths - followed by bowel cancer and breast cancer.

A range of blood tests for cancer has been announced by scientists and drugs companies over the last decade.

In 2000, AMDL, a Californian-company, announced it had developed a test for 13 of the most serious types of the disease from a single blood sample.

The company says its test works 84 per cent of the time but does not reveal which of the cancers the patient has.

A blood test for breast cancer has been developed at the John Wayne Cancer Institute in California, while a similar test is being investigated by Norway's DiaGenic ASA.

Dr Lesley Walker, of Cancer Research UK, said: "A number of blood tests to detect breast cancer are being investigated, which could be used to screen those most at risk and detect the disease earlier than current methods allow.

"But research in this area is at a very early stage so at the moment the use of such a test to diagnose patients with breast cancer remains on the horizon."

The Guernsey doctor who started collecting the samples in the 1960s did so in the hope they would later be used for research.