04 April 2008

Nicotine addiction genes increase the risk of lung cancer in smokers

Three independent groups of scientists have identified gene variants that contribute to the development of nicotine addiction and at the same time increase the risk of lung cancer in smokers. The research has been published in the journals Nature and Nature Genetics.

In total, scientists analyzed the genes of 35 thousand people of European origin. As a result, they were able to find two sites located on chromosome 15 that are directly related to the development of nicotine addiction and lung cancer. These gene variants encoding nicotine receptor proteins are very common – about every second person of European origin.

It turned out that smokers who have one copy of these genetic variants have a 28% higher risk of developing lung cancer than other smokers. On average, such people smoke one cigarette per day more than other smokers, the study showed.

Smoking carriers of two copies of these genetic variants smoke two cigarettes more on average. The risk of developing lung cancer in such people increases by 80%, compared with other smokers. As a result, the disease occurs in every fourth person from this group. For comparison, smokers who do not carry these gene variants have a 14% risk of developing lung cancer, which is about 10 times higher than non-smokers, the researchers reported.

Carrying unfavorable gene variants "contributes to the development of nicotine addiction and makes it difficult to quit smoking," said the head of one of the studies, Professor Christopher Amos from the Anderson Cancer Center (Houston).

The authors of the studies interpreted the reasons for the relationship between the carriage of unfavorable gene variants and the risk of cancer in different ways. According to representatives of the Icelandic company deCODE Genetics, an increased risk of lung cancer is associated with an increase in the number of cigarettes smoked. However, scientists from the Institute of Cancer Research, Cambridge University and Johns Hopkins University believe that nicotine acting on nicotine receptors can cause uncontrolled cell division, directly increasing the risk of cancer.

New data can explain why some smokers live to 90 years without getting cancer, as well as the fact that nicotine addiction does not develop in all smokers, scientists say. In the future, this information can be used to develop screening tests to identify people with an increased risk of lung cancer, as well as lead to the creation of new methods to combat nicotine addiction.

Source: Genetic Link Tied to Smoking Addiction – AP, 04/03/2008

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