By SETH BORENSTEIN
WASHINGTON - Scientists have pinpointed genetic variations that make people more likely to get hooked on cigarettes and more prone to develop lung cancer — a finding that could someday lead to screening tests and customized treatments for smokers trying to kick the habit.
The discovery by three separate teams of scientists makes the strongest case so far for the biological underpinnings of nicotine addiction and sheds more light on how genetics and lifestyle habits join forces to cause cancer.
"This is kind of a double whammy gene," said Christopher Amos, a professor of epidemiology at the M.D. Anderson Cancer Center in Houston and author of one of the studies. "It also makes you more likely to be dependent on smoking and less likely to quit smoking."
A smoker who inherits these genetic variations from both parents has an 80 percent greater chance of lung cancer than a smoker without the variants, the researchers reported. And that same smoker on average lights up two extra cigarettes a day and has a much harder time quitting than smokers who don't have these genetic differences.
The researchers disagreed on whether the variants directly increased the risk of lung cancer or did so indirectly, by causing more smoking.