Smoking’s legacy
Quitting smoking lowers the risk of heart disease and stroke quickly, but the risk of lung cancer goes down very slowly. A new study may help explain why.
The report, published in the online journal BMC Genomics, compared genes in the lung tissue of eight current smokers, 12 former smokers and four people who’d never smoked. The researchers found that smoking changes the activity of certain genes. In ex-smokers, some of those changes reverse to normal, but others don’t. The irreversible changes may permanently increase the lung cancer risk, the authors say.
Coauthor Dr. Stephen Lam, chairman of the British Columbia Cancer Agency’s lung tumor group in Vancouver, says the study was prompted by the fact that he and his associates were seeing lung cancer in patients who had stopped smoking 10 to 15 years earlier. “Something was perpetuating the damage,” he says.
One gene that did not return to its normal state was a tumor-suppressing gene that helps prevent cancer from forming. As a result, “when the cells become abnormal, the body is less capable of controlling them,” Lam says. Genes controlling inflammation were also permanently impaired, possibly adding to the cancer risk. “The best thing is to never start.”
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