Science shows the longer you smoke, the more mutations you get in your lung cells, increasing the risk of many types of cancer

Smoking wreaks genetic damage to different organs of the body and causes mutations in the DNA. Researchers at the Wellcome Trust Sanger Institute and the Los Alamos National Laboratory, as well as King’s College London, said that on average, smokers accumulate at least 150 extra mutations in every lung cell for each year that they smoked one pack of cigarettes per day.

The study provides a direct connection between the number of cigarettes smoked in a lifetime and its corresponding mutations in the tumor DNA, with the highest mutation rates found in lung cancers. Still, other parts of the body contained the mutations — bolstering the claim that smoking can cause different types of cancer.

The authors of the study discovered that smoking a pack of cigarettes each day prompted around 150 mutations in each lung cell each year. These mutations are noted to be the initial point for any number of genetic damage that may eventually develop into cancer. While the number of mutations may vary from each person, the study demonstrates the increased mutational load caused by tobacco.

“Before now, we had a large body of epidemiological evidence linking smoking with cancer, but now we can actually observe and quantify the molecular changes in the DNA due to cigarette smoking,” reports Dr. Ludmil Alexandrov, first creator from Los Alamos National Laboratory. “With this study, we have found that people who smoke a pack a day develop an average of 150 extra mutations in their lungs every year, which explains why smokers have such a higher risk of developing lung cancer.”

The mutation also hits other organs, according to the study. A pack of cigarettes a day caused about 97 mutations in each cell in the larynx, 39 mutations for the pharynx, 23 mutations for the mouth, 18 mutations for the bladder, and six mutations in the liver over the course of a year.

The process by which smoking can increase the risk of developing cancer in other parts of the body that do not interact with smoke has only been fully understood recently. Still, the study reported different ways on how smoking causes these mutations, based on the area of the body it affects.

Additionally, the study yielded five discrete processes of DNA damage caused by smoking cigarettes: the most prevalent of which is present in all cancers.

This gives weight to the claim that tobacco smoking can speed up a cell’s internal clock and may cause DNA mutations.

Scientists are positive that the results of the study will aid them in understanding the causes of cancer in the body and develop ways to counter it.

Professor Mike Stratton, a co-author of the study states: “We can also see the desperate attempts of our genome to defend itself against the damage wreaked by the chemicals in cigarette smoke or the damage from ultraviolet radiation. Our cells fight back furiously to repair the damage, but frequently lose that fight.”

The Centers for Disease Control and Prevention (CDC) lists smoking-related deaths as the leading preventable cause of death in the U.S., with one in five deaths recorded to be linked to smoking. The World Health Organization (WHO) pegs that number to seven million deaths worldwide: at least one million of those deaths are due to effects of second-hand smoke. (Related: Smoking causes up to 40% of cancer deaths in the US… so why are cigarettes still sold by pharmacies?)

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