30.01.20
Protective cells could diminish risk of lung cancer for ex-smokers
Cancer Research UK-funded researchers have found protective cells in the lungs of ex-smokers could explain why quitting smoking reduces the risk of developing lung cancer.
Scientists from the Wellcome Sanger Institute and UCL have found that when looked at alongside current smokers, people who had stopped smoking had more genetically healthy lung cells, which have much lower risk of developing into cancer.
The research, published today (Jan 30) is part of the £20m Mutographs of Cancer project, a Cancer Research UK Grand Challenge initiative. The project detects DNA ‘signatures’ that show the source of damage, to better understand the causes of cancer, and determine the ones we may not yet be aware of.
The study has shown that quitting smoking could do more than just stopping further damage to the lungs. It could also allow new, healthy cells to actively replenish the lining of our airways. This shift in proportion of healthy to damaged cells could help protect against cancer.
These findings show the benefits of stopping smoking completely, at any age.
Lung cancer is the most common cause of cancer death in the UK, accounting for 21% of all cancer deaths. Smoking tobacco damages DNA and hugely increases the risk of lung cancer, with around 72 per cent of the 47,000 lung cancer cases in the UK caused by smoking.
In the first significant study of the genetic effects of smoking on ‘normal’ non-cancerous lung cells, researchers analysed lung biopsies from 16 people including smokers, ex-smokers, people who had never smoked and children.
They sequenced the DNA of 632 individual cells from these biopsies and looked at the pattern of genetic changes in these non-cancerous lung cells.
Joint senior author 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.”
Dr Kate Gowers, joint first author from UCL, said: “Our study is the first time that scientists have looked in detail at the genetic effects of smoking on individual healthy lung cells. We found that even these healthy lung cells from smokers contained thousands of genetic mutations.
“These can be thought of as mini time-bombs waiting for the next hit that causes them to progress to cancer. Further research with larger numbers of people is needed to understand how cancer develops from these damaged lung cells.”
Image: Cancer Research UK