Tobacco products are the leading cause of lung cancer death in the United States, and they add up to around 90% of all lung cancer fatalities.
Scientists have always thought about why these deaths do not comprise a lot of smokers. The theory has suggested that genetics plays a role in determining this.
Certain people’s DNA repair genes are more active, which might protect them against cancer even if they smoke cigarettes on a regular basis. The cells lining their lungs are less prone to mutate over time.
The researchers used genetic profiles from 14 never-smokers and 19 light, moderate, and heavy smokers’ bronchi.
“These lung cells may live for years, even decades, and hence can acquire mutations with age and smoking,” says Albert Einstein College of Medicine epidemiologist and pulmonologist Simon Spivack.
“Of all the cell types in the lungs, these are the ones that are most prone to turn malignant.”
The data “unambiguously reveal” that mutations in the human lung grow with natural age, and that DNA damage is significantly more substantial in smokers.
The number of cigarettes smoked was connected to an increase in cell mutation rates. However, this risk increased after around 23 years of smoking a pack a day.
According to Spivack, “the heaviest smokers did not have the largest mutation load.”
“Our findings show that these people survived so long despite their extensive smoking because they were able to prevent additional mutation accumulation. This slowing of mutations might be due to these individuals’ well-developed systems for mending DNA damage and detoxifying cigarette smoke.”
The findings may explain why 80 to 90% of lifetime smokers do not get lung cancer.
DNA repair genes can be inherited or acquired, and the silence of repair genes has been linked to tumor formation in earlier studies.
Genes aren’t the only thing that influences a person’s chance of developing cancer. Dietary variables, for example, can change substances in the body that lead to tumor formation.
“We now want to create new tests that can detect someone’s potential for DNA repair or detoxification,” explains geneticist Jan Vijg.