Lung cancer risk: Ex-smokers benefit from lung regeneration

Lung cancer risk: Ex-smokers benefit from lung regeneration

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Study: This is how the lungs regenerate after smoking

Smoking is the most common and the largest preventable cancer risk. It is well known that quitting smoking is healthier. A research team has now shown that stopping smoking is much more than limiting damage. The lungs have exceptional regenerative abilities, in which damaged cells are replaced by healthy ones, thereby continuously reducing the risk of lung cancer.

Researchers at the Wellcome Sanger Institute in England deciphered the mechanisms by which the lungs recover from smoking. The team also showed that ex-smokers have four times more genetically healthy cells than smokers. The results were recently published in the renowned journal "Nature".

Three quarters of all lung cancer cases are caused by smoking

Lung cancer is the leading cause of cancer death in England, according to the Wellcome Sanger Institute. 21 percent of all cancer deaths are caused by lung cancer. Smoking massively damages the genetic material (DNA) and increases the risk of lung cancer enormously. Over 70 percent of all lung cancer cases are caused by smoking.

Smoking causes genetic errors

The study examined the genetic effects of smoking in smokers and ex-smokers for the first time. The researchers sequenced the DNA of 632 individual cells from biopsies and examined the pattern of genetic changes in the lung cells.

The research team showed that smoking in particular damages the DNA of cells that line the lungs. This creates genetic errors from which so-called driver mutations can develop. Cells with such a mutation receive a growth spurt and begin to multiply uncontrollably, which greatly increases the risk of lung cancer.

Smoking changes 90 percent of the lung cells

According to the study, the genetic changes are so extensive that active smokers have genetically modified more than nine out of ten lung cells. Not every genetic change is cancerous, but every fourth mutation caused by smoking has the potential to become cancerous.

Ex-smokers unexpectedly had many healthy lung cells

When the researchers examined the lung cells of ex-smokers, they were amazed to find that an unexpectedly large number of lung cells no longer have any genetic changes. Around forty percent of the lung cells were similar to those of non-smokers. Ex-smokers had four times less genetic damage in the lung cells than active smokers.

It is never too late to stop

"People who have smoked heavily for 30, 40 or more years often tell me that it is too late to stop smoking - the damage has already been done," explains Dr. Peter Campbell from the study team. However, the current study shows that it is never too late to quit smoking. According to Campbell, some participants had smoked over 15,000 packets of cigarettes - but a few years after they stopped, many of the lung cells showed no damage from tobacco use.

Mini time bombs in smokers' lung cells

"We found that even healthy lung cells from smokers contain thousands of genetic mutations," added lead author Dr Kate Gowers. These mutations can be seen as mini time bombs. Each of these cells could become cancerous. In an upcoming study, the team plans to investigate how genetically modified lung cells develop cancer.

Approach to new cancer treatments

"Our study is an important public health message and shows that it is really worth quitting smoking to reduce the risk of lung cancer," said Professor Sam Janes. Quitting smoking is more than just a limitation of the damage, but encourages the formation of cells that have not been damaged by smoking.

"Further research into this process could help to understand how some cells protect themselves from genetic mutations and cancer," said Janes. This could potentially lead to new cancer therapies.

If you stop smoking, you benefit twice

"It's a really motivating idea that people who quit smoking could benefit twice," adds Dr. Rachel Orritt of Cancer Research UK. On the one hand, further tobacco-related damage to the lung cells is prevented and, on the other hand, existing damage is compensated for over time by healthier cells.

For help quitting, see the article: Quit Smoking.

Author and source information

This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Graduate editor (FH) Volker Blasek


  • Wellcome Sanger Institute: Never too late to quit: protective cells could cut risk of lung cancer for ex-smokers (published: 29.01.2020),
  • Kate H. C. Gowers, Sam M. Janes, Peter J. Campbell, and others: Tobacco smoking and somatic mutations in human bronchial epithelium; in: Nature 2020,

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