THE ESSENTIAL
- Researchers have discovered why most smokers don’t develop lung cancer
- These results might make it possible to develop effective preventive measures.
- Lung cancer is the leading cause of cancer death in France and worldwide
Smoking is, to a large extent, the main cause of lung cancer, but only a minority of lifelong smokers, between 10 and 20%, develop the disease.
According to scientists at the Albert Einstein College of Medicine, some smokers may have robust mechanisms that limit mutations in lung cells, which would protect them from lung cancer.
These results published today in Nature Genetics might also help identify smokers who are at increased risk of contracting the disease and who therefore deserve particularly close monitoring.
An important step towards prevention
“These results might be an important step towards the prevention and early detection of lung cancer risk, instead of the Herculean efforts currently needed to combat the disease at an advanced stage, where the majority of health care expenditure and misery,” said Simon Spivack, MD, MPH, study co-lead author, professor of medicine, population epidemiology and health, and genetics at Einstein, and pulmonologist at Montefiore Hospital in New York.
New sequencing technique
The researchers developed a new sequencing technique called single-cell multiple displacement amplification (SCMDA) to compare the mutational landscape of lung epithelial cells that line the lung of two types of people: 14 never-smokers aged 11 to 86; and 19 smokers, ages 44 to 81, who had smoked a maximum of 116 pack-years. A pack-year of smoking corresponds to a pack of cigarettes smoked per day for one year.
The cells were taken from patients who were undergoing bronchoscopy for diagnostic tests unrelated to cancer. “These lung cells survive for years, even decades, and therefore can accumulate mutations with age and smoking,” Dr. Spivack said. “Of all the types of lung cells, these are among the most likely to become cancerous.”
More mutations
The researchers found that the mutations accumulated in the lung cells of non-smokers as they aged – and were significantly more numerous in the lung cells of smokers. “This study experimentally confirms that smoking increases the risk of lung cancer by increasing the frequency of mutations, as previously hypothesized,” said Dr. Spivack. “That’s probably one of the reasons why so few non-smokers get lung cancer.”
Another interesting finding: the number of cellular mutations detected in lung cells increased with the number of pack-years of smoking – and so did the risk of lung cancer. But the increase in cellular mutations stopped following 23 packet-years of exposure.
“The heaviest smokers did not have the highest mutation load,” Dr. Spivack said. “Our data suggests that these people were able to survive this long despite their heavy smoking because they were able to suppress the accumulation of mutations. caused to DNA or to detoxify cigarette smoke.”
Below is our Q&A program on lung cancer: