Three independent teams of researchers have found genes that may explain why some smokers get cancer and others do not, and why some people who never smoke also get the disease. Investigators say the discoveries could lead to better ways to prevent and treat one of the most lethal forms of cancer.
The teams in the United States, France and Iceland scoured the DNA of thousands of white smokers and non-smokers of European descent,with and without lung cancer, looking for genes that have been linked to smoking.
Researchers identified three genetic variants that if inherited, increase a person's risk of developing lung cancer from 30 to 80 percent compared to those who do not have the genes.
While cigarette smoking is considered the number one risk factor for lung cancer, only fifteen percent of smokers eventually develops the disease, leading doctors to suspect genetics.
Mark Lathrop, co-author of one of the three studies, says it appears many more genes play a role in lung cancer but have yet to be identified. "Undoubtedly with larger studies of the same sort, we'll be able to identify a number of further genetic factors that are involved in the predisposition," he said.
Investigators say that smokers who inherit a full complement of the genetic variants have a twenty-three percent increased risk of developing lung cancer.
In all three studies, investigators found a link between smoking and nicotine. But only one team of scientists identified a genetic variation that they say causes addiction to nicotine, including how much a person smokes.
For now, researchers say it's unlikely their work will lead to some kind of a genetics test to determine who is and is not at high risk for lung cancer.
"There's not a public health message here that you know you can find what version of the gene you have and decide whether to keep on smoking or not. Because then also you have to bear in mind that there are so many other diseases that are caused by smoking," said Paul Brennan of the International for Research on Cancer in Lyon, France, who is a senior author of one of the studies.
But investigators say identifying genetic variants in gives scientists targets that can lead to new drugs to treat and possibly prevent lung cancer, a leading cause of cancer death around the world.
Meanwhile, investigators say they are now conducting studies involving Asians and Americans of African descent to try to identify genetic abnormalities that increase the risk of lung cancer in those populations.