A blood test which may reveal the earliest signs of lung cancer is being developed by doctors looking after Chernobyl's cancer victims.

There has been an increase in lung cancers among those involved with the clean-up in the aftermath of the Ukrainian nuclear disaster in 1986.

However, these personal tragedies - and those likely to follow in years to come - have allowed doctors the opportunity to test theories about how to catch lung cancer before it spreads.

Lung cancer is one of the most common in the UK, but the most lethal, as it is not only resistant to treatment, but often well-advanced before it is spotted by doctors.

Currently, once it is obvious enough to be spotted on x-rays, the tumour has had time to grow and spread, and may be much harder to treat.

The group of scientists from the Laboratory of Biomedicine at Moscow State University believe they may have found a way to predict those at greatest risk of developing lung cancer simply by testing their blood.

Immune response

Even though the body's immune system cannot beat cancer, it still produces a response, creating antibodies targeted at proteins on the surface of cancer cells.

The Russian research is aimed at detecting signs of those antibodies in the blood.

The group found that patients with small cell lung cancer did have signs of the antibodies.

People free from cancer virtually never had those antibodies.

Dr Alexander Bazhin, who led the research, said: "The profile we found in the serum (blood) of patients with small cell lung cancer was only rarely found in those with other types of cancer, and it was practically never found in the control subjects."

The potential for a successful test was reinforced by the fact that the blood analysis picked up four out of five lung cancers, identifying them correctly on nine out of ten occasions.

However, Dr Bazhin said that no blood test could be used in isolation to pick up lung cancer.

However, the test provided ominous news for a group of former Chernobyl clean-up workers who, although they had lung disorders, had not yet fallen prey to cancer.

Their blood was found to be much more likely to carry the antibodies than that from healthy volunteers, confirming their "high risk" status for cancer.

Accuracy challenge

However, other scientists have warned that antibody tests may never be accurate or reliable enough to use to screen people for lung cancer.

Dr Siow Ming Lee, from University College London, said while the results might prove a good "marker" of how a particular patient was doing, it could not be specific enough to small cell lung cancer.

He said: "This is not a screening test - the research is very early days."