It’s never too late to quit cigarettes and slash the risk of developing lung cancer, according to a new study.
The lung cells actually start to repair the lining of your airways if you do stub out the deadly habit, the findings from the Wellcome Sanger Institute and UCL suggest. And those rejuvenated cells could help protect an ex-smoker against the deadly disease.
Lung cancer is the leading cause of death in the US — and has just a five-year survival rate, according to the American Lung Association.
Senior author of the study, Dr. Peter Campbell, from the Wellcome Sanger Institute, said: “People who have smoked heavily for 30, 40 or more years often say to me that it’s too late to stop smoking — the damage is already done.
“What is so exciting about our study is that it shows that it’s never too late to quit. Some of the people in our study had smoked more than 15,000 packs of cigarettes over their life, but within a few years of quitting many of the cells lining their airways showed no evidence of damage from tobacco.”
In Dr. Campbell’s study, researchers examined the genetic effects of smoking on “normal,” non-cancerous lung cells from 16 people including smokers, ex-smokers, people who had never smoked and children.
The researchers found that despite not being cancerous, more than nine out of every ten lung cells in current smokers had up to 10,000 extra genetic changes compared with non-smokers, and these mutations were caused directly by the chemicals in tobacco smoke.
More than a quarter of these damaged cells had at least one cancer-driver mutation, which explains why the risk of lung cancer is so much higher in people who smoke.
Unexpectedly, in people who had stopped smoking, there was a sizeable group of cells lining the airways that had escaped the genetic damage from their past smoking.
Genetically, these cells were on par with those from people who had never smoked — they had much less genetic damage from smoking and would have a low risk of developing into cancer.
The researchers found that ex-smokers had four times more of these healthy cells than people who still smoked — representing up to 40 percent of the total lung cells in ex-smokers.
These results highlight the benefits of stopping smoking completely, at any age.
Speaking about the study, published in Nature today, Professor Sam Janes, joint senior author from UCL and University College London Hospitals Trust, said: “Our study has an important public health message and shows that it really is worth quitting smoking to reduce the risk of lung cancer. Stopping smoking at any age does not just slow the accumulation of further damage, but could reawaken cells unharmed by past lifestyle choices.
“Further research into this process could help to understand how these cells protect against cancer, and could potentially lead to new avenues of research into anti-cancer therapeutics.”
Cancer Research UK have also dubbed the results of the study “really motivating” for smokers.
Dr. Rachel Orritt, Health Information Manager at the charity, said: “The results add to existing evidence that, if you smoke, stopping completely is the best thing you can do for your health. It’s not always easy to kick the habit, but getting support from a free, local Stop Smoking Service roughly triples the chance of success compared to going it alone.”
Lung cancer is the most common cause of cancer death in the US, accounting for nearly 25 percent of all cancer deaths, according to the American Cancer Society.
Smoking tobacco damages DNA and hugely increases the risk of lung cancer, with around 80 percent of cases caused by smoking.
It is estimated that around 229,000 cases of lung cancer will be diagnosed in the US in 2020.
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