Cigarette smoking is the number one risk factor for lung cancer, and tobacco products cause up to 90 percent of lung cancer deaths in the United States alone.
Without a doubt, the surest way to protect yourself from lung cancer is to avoid smoking cigarettes, and yet, at the same time, it is also true that not all lifelong smokers are doomed to develop lung cancer. In fact, the vast majority do not develop it. Scientists have long wondered why, and a new study supports the idea that genetics play a role in this.
Among people who smoke but never get lung cancer, scientists have found an inherent advantage. The cells lining their lungs seem less likely to mutate over time. The results of a new study published in the scientific journal Nature suggest that DNA repair genes are more active in some individuals, which can protect against cancer, even when cigarettes are smoked regularly.
The study used genetic profiles taken from the bronchi of 14 non-smokers and 19 light, moderate and heavy smokers. Surface cells collected from participants’ lungs were sequenced individually to measure mutations in their genome.
“These lung cells survive for years, even decades, and can therefore accumulate mutations with age and smoking.” “Of all the types of lung cells, they have the highest chance of becoming cancerous,” explains Simon Spivak, an epidemiologist and pulmonologist at the Albert Einstein School of Medicine.
According to the authors of the study, its results “unequivocally show” that mutations in the human lungs increase with natural age, and in smokers DNA damage is even more significant. Tobacco smoke has long been linked to causing DNA damage in the lungs, but new research shows that not all smokers are at equal risk of developing lung cancer.
While the amount of cigarettes a person smokes is associated with an increase in the rate of cell mutation, after approximately 23 years of smoking one pack per day, that risk reaches its peak.
“The biggest smokers did not have the biggest load of mutations. Our data suggest that these individuals may have survived so long despite their heavy smoking because they were able to suppress further accumulation of mutations. “This equalization of mutations can result in these people having very specialized systems for repairing DNA damage or detoxifying cigarette smoke.”
The results of the study could help explain why 80 to 90 percent of lifelong smokers never get lung cancer. It may also help to explain why some people who do not smoke develop tumors at all. While toxic tobacco smoke appears to cause additional cell mutations in the lungs, whether those mutations develop into tumors depends on how well the body can repair DNA or reduce DNA damage.