TORONTO: The body does not recover fully from the harmful affects even years after you quit smoking, a new study reveals.
Smoking is already known to cause 87 percent of lung cancer deaths. It is also responsible for many other cancers and health problems.
Scientists in Canada assayed gene expression levels in tissue scraped from the airways of four non-smokers (who had never smoked), eight current smokers, and twelve former smokers who had gone without a cigarette for at least one year and up to 32 years.
They found that some genes with altered expression in smokers had returned to normal levels in former smokers. But the expression of another 124 genes had not returned to normal.
The results revealed that those who quit smoking reduce their risk of disease but it is not going back to zero. The results of the study could provide a molecular explanation for the continued increased risk of lung cancer and other pulmonary ailments among former smokers.
When smokers quit, their bodies gradually begin to undo the damage cigarettes have wrought. But contrary to popular belief, not all of the body's systems make a full recovery, reported the online edition of Nature magazine.
Although the risk of heart disease, for example, eventually returns to that of a non-smoker, the risk of getting lung cancer and emphysema - a progressive lung condition that leaves sufferers struggling for breath - remains elevated even if the patient hasn't smoked a cigarette in decades.
The study by Raj Chari, a cancer biologist at the British Columbia Cancer Research Centre in Vancouver, Canada and his co-workers appeared in journal BMC Genomics on Thursday.