Lung cancer claims approximately two million lives a year in the world, according to the World Health Organization (WHO). Tobacco use is responsible for between 80% and 90% of cases of this disease.
Smoking this harmful substance causes between 1,000 and 10,000 abnormal mutations and alterations for each cell and thus leaves a free path to tumor formation.
A study, published Wednesday in Nature, shows that quitting this habit, awakens healthy cells that help the lungs to regenerate.
Peter Campbell, lead author of the study and researcher at the Wellcome Sanger Institute says that people who have been smoking for 30, 40 years and who think it is too late to quit smoking are wrong.
“The most incredible thing about our study is that it demonstrates that despite smoking 15,000 packs of cigarettes over a lifetime, as one of our participants, some of the cells show no damage due to tobacco,” he explains.
The team of researchers from Campbell, the Wellcome Sanger Institute and University College London (UCL), has sequenced the genome of 632 colonies of the bronchial epithelium of 16 people: three children, four who never smoked, six who quit and three current smokers.
All cells that were analyzed, even those of non-smokers, showed an increase in mutations due to aging. Each year, it is estimated that cells allow 22 additional mutations.
This figure should be increased, according to study data, to 2,330 in former smokers and 5,300 in current ones. However, unknown cells so far did not match expectations.
Present only in ex-smokers, these tiny elements showed similar levels of mutation to those found in non-smokers of the same age.
These cells, according to the authors, are “clearly protective against cancer”, absent, or still imperceptible, in the organs of current smokers and four times more frequent in participants who had quit smoking.
The cells have almost no carcinogenic footprints and their telomeres (limbs of the chromosomes) are longer, which means that they have not suffered many divisions compared to the affected cells.
The study states that it is not clear how these cells are born, how they resist the mutations that their neighbors suffer and why, above all, they appear in people who have quit smoking and not also in current smokers.
One of the possibilities, although it deserves clarification, is that these stem cells that act as heroes, occupy a protected area in the submucosal glands and expand after lung injury. This physically separated niche could explain its impermeability against damage.
The benefits, after stopping smoking, begin immediately, as the authors write, and increase over time. The appearance of these mysterious cells that take off the head after the battle, shows the capacity of recovery and regeneration of the lung at any age.
Quitting smoking at any age not only slows the accumulation of more damage but also awakens unharmed cells, as confirmed by Professor Sam Janes of the UCL and co-author of the study. “With additional research, we could understand how these cells protect against cancer, which could lead to new therapies against this disease,” he concludes.
“It is always important to prevent and prevent smoking from starting, but now we have a confirmation that, in a certain way, is reversible,” explains the expert.
But, although the tissue of the respiratory system can be restored, it will never be the same as it was before a person begins smoking.
Of course, the accumulated risks are reduced over time. The population of new cells acts and ends up dominating, and although the risk of tumors will never disappear, the probability that they appear will tend to decrease.
According to experts, 40% of cancers are preventable and “the ball is on our court”, since that percentage of tumors is related to the lifestyle people choose to adopt.
The study also shows that the genetic damage of tobacco affects the vast majority of the epithelial cells of our lungs. Also that there is a percentage of cells, about 25%, that have genetic alterations that cause cancer.