Do young smokers damage lung DNA?

Smoking during childhood or adolescence may lead to lasting or even permanent genetic damage in the lungs that increases the risk of lung cancer, even after the smoker quits, researchers say.

The developing lungs of young people may be especially vulnerable to cigarette smoke, the scientists said. They said their research linked the amount of damage to the age when people started smoking, regardless of how many years they smoked or how recently they had quit.The scientists, from the University of California at San Francisco School of Medicine, said the findings were particularly alarming, given the number of teenagers who smoke.

"If we're right," said Dr. John K. Wiencke, who led the research effort, "it says that something happens in adolescence that changes you, perhaps forever."

The findings, published Wednesday in the Journal of the National Cancer Institute, are based on an analysis of blood and tissue from 143 patients with lung cancer. The researchers looked for alterations in DNA, which are known to be caused by tobacco and to be linked to cancer.

Levels of alterations, called DNA adducts, were lowest among patients who had never smoked. In ex-smokers they were somewhat higher and in people who still smoked, higher still. But in ex-smokers, the highest levels were found in those who started smoking as children or teenagers, regardless of when they had quit.

The study did not compare the patients' adduct levels to those of people who do not have lung cancer. Nevertheless, other researchers said it was an important and surprising finding.

Dr. John Minna, a lung cancer expert and director of the Hamon Center for Cancer Research at the University of Texas Southwestern Medical Center in Dallas, said the DNA adducts measured by researchers were a good indicator of smoking's genetic damage.

"Right now about half of new lung cancer cases are occurring in former smokers," Minna said. "If it turns out that a very brief period of smoking during adolescence, or starting then, will have this long-lasting effect in terms of cancer development, even if you stop at a young age, that is frightening."