Is it never too late to stop smoking?

Hiding from the catastrophe: the protective lung cell population that replenishes damaged cells in ex-smokers.

Writer: Alexandra David
Editor: Jennifer Marx
Artist: Emily Wang

State-of-the-art results were recently published in Nature by Yoshida and colleagues, who analyzed a population of lung cells that line the airways across 16 people, including smokers, ex-smokers, those who never smoked, and children. The results were astonishing – the subjects with a history of smoking had a specific population of cells with a mutational damage profile as low as those expected in individuals that never smoked.

Tobacco smoke is by no means beneficial to you, or to your lungs. In fact, 72% of lung cancer deaths in the UK are caused by exposure to tobacco smoke, and smoking has such profound effects on the mutational burden of your lungs that it can add between 1,000 and 10,000 mutations per cell. In an article for the Wellcome Sanger Institute, Dr. Kate Gowers from UCL compares these damaged cells to ticking time-bombs, waiting for the next mutation to tip them into cancerous cells. 

In the past, it was thought that mutations to your cells were irreversible, even after quitting smoking. However, in their research, Yoshida and colleagues point to a mitotically quiescent population of cells that are able to hide and escape the tobacco-induced mutations. When you quit smoking, these cells can magically activate and replenish the damaged cells, leading to up to four times more healthy cells in ex-smokers than in smokers. Even more astonishing is that the effects can be seen almost immediately after quitting.

These results highlight that there are significantly larger benefits to quitting other than just inhibiting additional lung damage. The authors emphasize that it is really never too late to quit, pointing out that some subjects had smoked more than 15,000 packs of cigarettes over their life, but after a few years of stopping, a large amount of cells in their airways showed little mutational damage left from smoking tobacco. As such, our lungs seem to have a striking regenerative capacity that can reverse damage caused by smoking.

This doesn’t mean that you can keep smoking indefinitely without facing serious health consequences. Heavy smokers who don’t quit are still at very high risk for lung cancer, and tobacco smoke can still significantly damage deeper lung tissue, leading to chronic, irreparable diseases such as emphysema. The study serves to demonstrate that it is never too late to quit, but the sooner you do, the better.


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