Smoking damages your DNA permanently

Smoking pack of cigarettes a day causes average of 150 DNA mutations a year creating high risk of cancer & death.

HEALTH

Smoking damages your DNA permanently 

One DNA mutation for every 50 cigarettes smoked
04/11/2016
AFP News Agency

Smoking a pack of cigarettes a day causes an average of 150 mutations a year in lung cells.

This is a scientific finding of a new study that identifies specific ways that cigarette smoke exposure damages DNA.

The research, published Thursday in the journal Science, was carried out by an international group of researchers from Britain's Wellcome Trust Sanger Institute and the Los Alamos National Laboratory in the United States (see here).

NEW RESEARCH FINDINGS

The research analyzes and compares tumors.

The study provides the first accurate measure of the devastating genetic damage smoking inflicts not only in the lungs but also in other organs of the body not directly exposed to smoke.

It was previously known that smoking contributes to at least 17 types of human cancers.

It had remained unclear though exactly how cigarettes caused tumors.

DNA DAMAGE NOT ONLY IN LUNGS

Although the researchers saw the largest number of genetic mutations in lung tissue, other parts of the body also displayed changes in DNA, helping explain how smoking causes various types of cancer.

Cigarettes contain more than 7,000 different chemicals, of which 70 are known to be carcinogenic, the researchers said, pointing to the complexity of how smoke interacts with the body.

"This study offers fresh insights into how tobacco smoke causes cancer," said Ludmil Alexandrov of the Los Alamos National Laboratory, one of the study's main co- authors.

MORE GENETIC MUTATIONS MEANS HIGHER CHANCE OF CANCER

"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," he added.

"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."

In the first comprehensive analysis of the DNA of cancers linked to smoking, the scientists studied more than 5,000 tumors, comparing smokers' cancers with those of people who had never smoked.

They found specific molecular features of damage in the smokers' DNA, determined by the number of those mutations in different tumors.

MOUTH, LIVER, BLADDER, LARYNX & PHARYNX ALSO AFFECTED

Although the number of mutations within cancer cells varies between people, the new study identifies  additional mutations in other body organs that smoking causes.

Smoking a pack a day causes an estimated average of 97 mutations in each cell of the larynx (in the throat); 39 in the pharyn (in the throat); 23 in the mouth; 18 in the bladder; and six mutations in every cell of the liver each year.

The research shows at least five distinct ways smoking damages DNA, the most common of which is found in most types of cancer: accelerating the speed of a cellular clock that appears to mutate DNA prematurely.

ARCHAEOLOGICAL DNA RECORD OF EACH CANCER GENOME

But the new study of smoking-related cancers can help scientists better understand how all cancers develop and, possibly, how they can be prevented, Mike Stratton of Wellcome Trust Sanger Institute said.

"The genome of every cancer provides a kind of 'archaeological record,'" in the DNA code, reflecting the exposure that causes mutations, he added.

SMOKING RESPONSIBLE FOR 6 MILLION DEATHS A YEAR

Smoking -- the largest preventable cause of death -- is responsible for at least six million deaths a year worldwide.

If current trend continues, the World Health Organization (WHO) says, smoking will kill more than a billion people in the 21st century.

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