FOCUS ON WHITE SMOKERS FOCUS ON WHITE SMOKERS Scientists who discovered a genetic link to smoking addiction and lung cancer have calculated smokers' cancer risk based on whether they have certain genetic variations. The study only covered white people of European descent. Studies of other populations will be done soon and may yield different results. The study found that white smokers have a: 23 percent chance of getting lung cancer if they inherited these genetic differences from both parents.

23 percent chance of getting lung cancer if they inherited these genetic differences from both parents. 18 percent chance of lung cancer if they inherited the genetic differences from one parent.

14 percent chance of lung cancer without the genetic variations. In general, people who have never smoked have less than a 1% chance of getting lung cancer. The scientists' findings on non-smokers with these genetic variants are contradictory. Researchers say they need to study a larger number of non-smokers. Three independent research teams have found genetic variations that increase the risk of lung cancer, a finding that may help explain why some smokers develop the disease and others don't. People with one of the gene variants have a 30% higher risk of lung cancer, and those with two have an 80% higher risk, says Paul Brennan, lead author of one of the papers. They were released today in Nature. Another study, also in Nature, finds the same variations also make people more likely to get addicted to tobacco and smoke more. The other reports do not strongly link the variations to smoking. But the scientists agree the variations are located in an area that includes genes that make up the building blocks of nicotine receptors — docking stations that allow nicotine to latch onto cells. Research shows nicotine can spur cells to reproduce without dying and can cause tissue to form new blood vessels, says Christopher Amos, the main author of a third paper published in the journal Nature Genetics. Fewer than 20% of smokers or former smokers develop lung cancer, Amost says. It's possible that genetic factors protect some people but put others at greater risk, says Amos of Houston's M.D. Anderson Cancer Center. Nora Volkow, director of the National Institute for Drug Abuse, says the studies could one day lead to ways to treat nicotine addiction. The National Cancer Institute's Stephen Chanock, who wrote an accompanying editorial in Nature, says the studies are still preliminary. Researchers have not yet mapped the genes, for example. Many other genetic variants probably are involved in a disease as complex as lung cancer, Channock says. He also notes that smoking causes many deadly conditions, including heart attacks, strokes and emphysema. "This isn't telling us who can get away with smoking and who can't," he says. Enlarge By Hocine Zaourar, AFP/Getty Images Turkish students light up their cigarettes in Istanbul. Researchers say there is a genetic underpinning that makes some more likely to become addicted to smoking. Conversation guidelines: USA TODAY welcomes your thoughts, stories and information related to this article. Please stay on topic and be respectful of others. Keep the conversation appropriate for interested readers across the map.