Mutation Alert! Smoking Changes DNA Permanently, Study Finds

This may make you finally quit that puffing. Scientists have recently discovered that a pack-a-day smoker generates at least hundreds of DNA mutations each year. What's even more alarming is that the mutations are permanent and irreversible.

As per the study published in the journal Science, the mutations are not just confined in the lungs but are also spread across the whole body.

Using computer simulations, the researchers analyzed somatic mutations and DNA methylation in more than 5,000 cancer cells. About half came from smokers and the rest came from non-smokers. This allowed the researchers to compare between the smoking and non-smoking samples.

The researchers found out that cancer cells found in smokers had 150 mutations in lungs, 97 in larynx, 39 in pharynx, 23 in mouth, 18 in bladder and 6 in liver.

"This study offers fresh insights into how tobacco smoke causes cancer," Dr. Ludmil Alexandrov, Oppenheimer Fellow at Los Alamos National Laboratory and co-lead author of the study said in a statement.

Although it is widely known that smoking triggers the development of 17 cancers, the mechanisms by which it causes cancer have previously remained elusive. This study reveals how it does.

"Our analysis demonstrates that tobacco smoking causes mutations that lead to cancer by multiple distinct mechanisms. Tobacco smoking damages DNA in organs directly exposed to smoke as well as speeds up a mutational cellular clock in organs that are both directly and indirectly exposed to smoke."

With its small size, a tobacco smoke contains a shocking amount of chemicals, and seventy of them are known to cause cancer. The researchers also found out that smoking also increases the rate of premature mutations.

Researchers say analyzing tumor DNA may help explain the underlying causes of other cancers, particularly cancer that develops in parts of the body that are not actually exposed to smoke.

Professor Sir Mike Stratton, joint lead author from the Wellcome Trust Sanger Institute, Cambridge, UK, said: "The genome of every cancer provides a kind of 'archaeological record,' written in the DNA code itself, of the exposures that caused the mutations that lead to the cancer. Our research indicates that the way tobacco smoking causes cancer is more complex than we thought. "