Studies suggests that cancer risk is not just down to lifestyle.
Jump to full article: Nature, 2008-04-02
Author: Michael Hopkin
Intro: Amongst smokers, genetics may raise the risk of lung cancer by 80%.
Three independent genetic studies have found some of the strongest evidence yet that your genes influence your risk of developing lung cancer.
Lung cancer, the most common killer cancer in the world, is largely caused by smoking. Tobacco is thought to be responsible for about 5 million premature deaths every year and smoking is still clearly the largest risk factor. But the new results suggest that, amongst smokers, some people may be as much as 80% more at risk than others thanks to their genes.
People who have never smoked might also have a slightly increased risk of developing lung cancer and similar problems, although the three studies disagree on whether this is actually the case. It is not clear whether the genetic effect occurs independently of smoking, or whether the genes raise the risk of cancer by exacerbating nicotine addiction. . . .
A third study3, involving almost 6,000 cancer cases and led by Christopher Amos of the University of Texas M. D. Anderson Cancer Center in Houston, also found that the gene variants raise cancer risk independently of smoking behaviour.
Stefansson, in contrast, believes that the genes promote cancer by making people more vulnerable to nicotine addiction. This view is supported by the fact that the genes for the brain's nicotine receptors are found in the same region of chromosome 15 as the genetic mutations.
People in Stefansson's study group tended to be more heavily addicted to smoking if they had more copies, or 'alleles' of the gene variants. "In our study, we found if you have one allele you smoke about one more cigarette per day; if you have 2 alleles you average two more cigarettes per day," he says.
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