Not all cigarette smokers develop lung cancer – Study says

NEWS DIGEST – Cigarette smoking is one of the main causes of lung cancer, however, only a few smokers develop the disease. Scientists at Albert Einstein College of Medicine, say that some smokers may have robust mechanisms

A new study published in Genetics Nature suggests that not all cigarette smokers develop lung cancer due to genetic mutations that protect them from lung cancer by limiting mutations.

Dr Simon Spivack, professor of medicine, a co-senior author of the study said, “the study may help to improve an important step toward the prevention and early detection of lung cancer risk and away from the current herculean efforts needed to battle late-stage disease, where the majority of health expenditures and misery occur.”

The study found that mutations accumulated in the lung cells of non-smokers as the age vary significantly in quantity to that of smokers.

“The researchers confirmed that smoking increases lung cancer risk by increasing the frequency of mutations, as previously hypothesized,” Spivack said, adding that “this may likely be one of the reasons why so few non-smokers get lung cancer, while 10 per cent to 20 per cent of lifelong smokers do.”

The researchers compared the mutational landscape of normal lung epithelial cells from two types of people: 14 never-smokers, ages 11 to 86; and 19 smokers, ages 44 to 81, who had smoked a maximum of 116 pack years. (One pack-year of smoking equals 1 pack of cigarettes smoked per day for one year).

“The heaviest smokers did not have the highest mutation burden. Our data suggest that these individuals may have survived for so long despite their heavy smoking because they managed to suppress further mutation accumulation. This levelling off of mutations could stem from these people having very proficient systems for repairing DNA damage or detoxifying cigarette smoke,” Spivack said.

The study also proves that the number of cell mutations detected in lung cells increased in a straight line with the number of pack-years of smoking and, presumably, the risk for lung cancer increased as well. But interestingly, the rise in cell mutations halted after 23 pack-years of exposure.

It has long been assumed that smoking leads to lung cancer by triggering DNA mutations in normal lung cells. “But that could never be proven until our study, since there was no way to accurately quantify mutations in normal cells,” said Jan Vijg.

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