Cancer hope as lungs of ex-smokers ‘regenerate’
SMOKERS whose lungs have been damaged can still regrow healthy cells, cutting their risk of cancer.
Healthy cells are able to replenish the lining of the airways even in people who had smoked 15,000 packs of cigarettes – a pack a day for 40 years.
Scientists said their findings show it is never too late to kick the habit.
A team from the Wellcome Sanger Institute and University College London (UCL) analysed lung samples from 16 people, including smokers, ex-smokers, people who had never smoked, and children.
They found that in former smokers up to 40 per cent of their total lung cells were healthy, compared to just 10 per cent in current smokers.
Study author Dr Peter Campbell said: “People who have smoked heavily for 30 or more years often say it’s too late to stop – that 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.”
Many lung cells in current smokers had up to 10,000 extra genetic mutations, compared with non-smokers.
The mutations, caused by chemicals in smoke, can cause the cells to divide uncontrollably and turn cancerous.
Dr Rachel Orritt, from Cancer Research UK which funded the study, said: “It’s a really motivating idea that people who stop smoking might reap the benefits twice over – by preventing more tobacco-related damage to lung cells and by giving their lungs the chance to balance out some of the existing damage with healthier cells.
“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 triples the chance of success.”
In people who had stopped smoking, researchers noticed a group of cells lining their airways that had escaped genetic damage, on par with those who had never smoked.
Professor Sam Janes, joint senior author from UCL, said: “Our study has an important public health message – it really is worth quitting smoking to reduce the risk of lung cancer.
“Stopping smoking at any age doesn’t just slow the accumulation of further damage, but could reawaken cells unharmed by past lifestyles.”
However, while the study showed that healthy lung cells could start to repair the lining of airways, smoking still causes irreversible damage deeper in the lung that can lead to emphysema – chronic lung disease.
Three quarters of the UK’s 47,000 annual lung cancer cases are caused by smoking. The disease accounts for 21 per cent of cancer deaths.