Smokers could be shown their risk of developing lung cancer by using a new genetic test, researchers say.

Cigarette smoking is the cause of nearly all lung cancers. The risk increases with the number and type of cigarettes smoked.

Up to 15 per cent of smokers develop the disease, which scientists believe could be indicated by patterns of gene activity in the lungs.

They have identified an 80-gene biomarker that could distinguish between smokers with and without lung cancer.

Lung cancer is the deadliest form of cancer in Britain, killing 92 people a day on average. It is often not discovered until a late stage. Nine out of ten victims contract it through active or passive smoking.

The proposed test suggests a way of letting smokers know that they are not expected to suffer lung cancer because of their habit.

Identifying at an early stage which smokers are likely to develop cancer and which are not could save many lives, as the disease kills up to 85 per cent of its victims within five years.

But smoking has many other harmful effects. Chiefly, it greatly increases the risk of heart disease, and can trigger lung conditions such as emphysema and chronic bronchitis.

The new study involved the gene-profiling of 129 current and former smokers who had undergone normal lung examination tests for suspected cancer. The patients were monitored until they were either given the “all clear”, or a definite diagnosis of lung cancer.

A particular pattern of activity involving 80 genes was found in 90 per cent of the patients in whom the disease was confirmed.

In comparison, routine bronchoscopy tests picked up 35 per cent of patients who eventually developed cancer.

The scientists, led by Avrum Spira, from Boston University in the US, believe that the gene test could provide an earlier warning of lung cancer than standard procedures.

The researchers write in the journal Nature Medicine: “Our biomarker might be useful as a screening tool for lung cancer among healthy smokers.”

But a spokeswoman for Ash, the public health charity, said yesterday that smokers were at risk from a number of other cancers. “Smoking accounts for one third of all cancer cases and does irreparable damage to the respiratory and immune systems. While this test might show the signs of lung cancer it should not be taken as an indication for people to carry on smoking because they are still at risk of causing illness to themselves, and to others through the secondhand effects of their smoke.”

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