Monday February 26, 2018

Smoking a Pack of Cigarettes each Day Causes 150 Mutations in Every Lung Cell, say Scientists

Smoking kills six million people a year worldwide and, if current trends continue, the World Health Organization predicts more than 1 billion tobacco-related deaths this century

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FILE - New findings show that smoking causes devastating genetic damage, or mutations, in the cells of various organs in the body. VOA
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Scientists have found that smoking a pack a day of cigarettes can cause 150 damaging changes to a smoker’s lung cells each year.

The findings come from a study of the devastating genetic damage, or mutations, caused by smoking in various organs in the body.

Published Thursday in the journal Science, the researchers said the findings show a direct link between the number of cigarettes smoked in a lifetime and the number of mutations in the DNA of cancerous tumours.

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The highest mutation rates were seen in lung cancers, but tumors in other parts of the body — including the bladder, liver and throat — also had smoking-associated mutations, they said. This explains why smoking also causes many other types of cancer beside lung cancer.

Smoking kills six million people a year worldwide and, if current trends continue, the World Health Organization predicts more than 1 billion tobacco-related deaths this century.

Cancer is caused by mutations in the DNA of a cell. Smoking has been linked with at least 17 types of cancer, but until now scientists were not clear on the mechanisms behind many of them.

Ludmil Alexandrov of Los Alamos National Laboratory in the United States, one of those who carried out the research, explained that in particular, it had until now been difficult to explain how smoking increases the risk of cancer in parts of the body that don’t come into direct contact with smoke.

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“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,” he said.

This study analyzed over 5,000 tumors, comparing cancers from smokers with those from people who had never smoked.

It found certain molecular fingerprints of DNA damage — called mutational signatures — in the smokers’ DNA, and the scientists counted how many of these were in different tumors.

In lung cells, they found that on average, smoking a pack of cigarettes a day led to 150 mutations in each cell every year.

Each mutation is a potential start point for a “cascade of genetic damage” that can eventually lead to cancer, they said.

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The results also showed that smoking a pack of cigarettes a day led to an average 97 mutations in each cell in the larynx, 39 mutations for the pharynx, 23 for the mouth, 18 for the bladder, and six mutations in every cell of the liver each year.

Mike Stratton, who co-led the work at Britain’s Wellcome Trust Sanger Institute, said it was a bit like digging into the archaeology of each tumor.

“The genome of every cancer provides a kind of archaeological record, written in the DNA code itself, of the exposures that caused the mutations,” he said. “Looking in the DNA of cancers can provide provocative new clues to how [they] develop and thus, potentially, how they can be prevented.” (VOA)

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  • Ruchika Kumari

    Smoking is injuries for health….everyone knows….still smokers are not quitting it

  • Shivani Vohra

    Smoking is really injurious to health.

Next Story

Cigars, Pipes Tied To Same Risks As Cigarettes

Traditionally, doctors have asked just whether people smoked cigarettes, but they should instead be questioning patients more broadly about tobacco use

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E-cigarettes
E-cigarettes is considered to be safer than tobacco cigarettes. Pixabay
  • Cigarettes are not the only tobacco products which can cause death
  • Other tobacco products like cigars and pipes are just harmful
  • All these tobacco products can cause cancer

Cigarettes are not the only type of tobacco products that can lead to premature death or fatalities from smoking-related cancers, a U.S. study confirms.

While people who exclusively smoke cigarettes have twice the risk of premature death from all causes compared to people who avoid tobacco altogether, exclusive cigar smokers have a 20 percent higher risk of early death, researchers report in JAMA Internal Medicine.

Cigarettes are not the only harmful tobacco products available in the market. Pixabay
Cigarettes are not the only harmful tobacco products available in the market. Pixabay

When it comes to fatalities from specific cancers that have been tied to tobacco use, cigarette smokers have four times the risk of people who never used tobacco, but cigar smokers are 61 percent more likely to die of these cancers and pipe users have 58 percent higher odds.

“We knew exclusive users of cigars and pipes were at greater risk of disease than people who do not use tobacco,” said lead study author Carol Christensen of the U.S. Food and Drug Administration’s Center for Tobacco Products. “However, this study provides information that reflects today’s patterns of tobacco use.”

Also Read: Banning E-Cigarettes Deprives Indian Smokers of a Less Harmful Alternative: Experts

These data “underscore the importance of complete quitting,” Christensen said by email.

For the study, researchers examined nationally representative survey data, collected starting in 1985, from 357,420 participants who were followed through 2011.

Overall, 203,071 people, or about 57 percent, never used tobacco at all. Another 57,251 participants were current daily cigarette smokers, while 9,414 said they had a less frequent habit and 77,773 were former cigarette smokers.

In addition, 531 people were current daily cigar smokers, while 608 individuals used cigars less frequently and 2,398 had quit.

For pipes, 1,099 participants had a current daily habit, while 78 people used pipes less often and 5,237 had quit.

Pipes, hookahs and all other tobacco products are just as harmful as a cigarette. post-gazette.com
Pipes, hookahs and all other tobacco products are just as harmful as a cigarette. post-gazette.com

During the study period, 51,150 people died of all causes.

With a daily cigarette, cigar or pipe habit, people had an elevated risk of death from tobacco-related cancers including malignancies of the bladder, oesophagus, larynx, lung, mouth and throat, and pancreas.

Nondaily users

Even with a nondaily cigarette habit, people were more than six times more likely to die of lung cancer than individuals who never used tobacco. They also had more than seven times the risk of dying from a chronic obstructive pulmonary disease, more than four times the odds of death from oral cancers, and 43 percent higher odds of death from a circulatory system disorder.

Current cigar smokers had more than three times the odds of dying of lung cancer, and for current pipe smokers, the risk was 51 percent higher, compared with never-smokers.

The results were limited, however, by the relatively small numbers of cigar and pipe smokers in the sample, the authors noted.

Cigarettes, hookah, pipes, cigars all are equally harmful.
Cigarettes, hookah, pipes, cigars all are equally harmful.

Another limitation was that survey questions about tobacco use changed over time and didn’t determine how often nondaily smokers might have used cigarettes, cigars or pipes.

Even so, the results suggest that doctors may need to broaden how they discuss smoking with patients to make sure people understand they’re at risk even when they don’t have a daily habit, said Dr. Michael Ong of the University of California-Los Angeles and VA Greater Los Angeles Healthcare System.

Also Read:  Beware! Vapor smoke from E-cigarettes are just as harmful, says a new research

“Patients often do not associate the occasional use of cigar or pipes with health risks, but this study shows that current, particularly daily, cigar use is associated with increased overall risk of death,” Ong, who wasn’t involved in the study, said by email.

Doctors also need to broaden their message about smoking and cigarettes to include other tobacco products that are becoming more popular, said Judith Prochaska, a researcher at Stanford University in California who wasn’t involved in the study.

e-cigarettes
Smoking e-cigarettes are not a healthier alternative to smoking. cigarettes Pixabay

Traditionally, doctors have asked just whether people smoked cigarettes, but they should instead be questioning patients more broadly about tobacco use, Prochaska said by email.

“The tobacco landscape has been changing dramatically,” Prochaska added. “While cigarettes remain the primary tobacco product used, cigars, smokeless tobacco, e-cigarettes, hookah, and even pipe tobacco have seen gains in use, while cigarette use in the U.S. has been declining.” VOA