New research has shown that lung tissue can be permanently damaged by smoking, meaning that smokers who have quit still stand the possibility of getting lung cancer.
The study, from the British Columbia Cancer Research Centre in Vancouver, has shown that smoking can permanently affect the actions of key genes, particularly those that may be involved in cancer susceptibility.
Scientists looked at cell samples from eight current smokers, 12 ex-smokers and 4 non-smokers. They discovered that, after stopping, some gene changes would reverse after being smoke-free for a year or more.
However, a few genes which helped the body repair its DNA had their activity levels reduced from the effects of smoking.
According to the BBC, head of the research Raj Chari said: "Those genes and functions which do not revert to normal levels upon smoking cessation may provide insight into why former smokers still maintain a risk of developing lung cancer."
A spokeswoman from the pressure group Action on Smoking and Health spoke with the BBC, emphasising that quitting smoking still has great health benefits: "Although former smokers do still have a slightly increased risk of lung cancer compared with someone who has never smoked, it is nowhere near as high as the risk of lung cancer to someone who is a current
Independent advice on private healthcare