Sunday December 15, 2019

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

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)

  • 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

One-Third Patients Diagnosed with Lung Cancer Have Depression

One-third of lung cancer patients have depression says study

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Depression- lung cancer
Studies have found that About one-third of patients newly diagnosed with the most common form of lung cancer show signs of depression. Lifetime Stock

About one-third of patients newly diagnosed with the most common form of lung cancer have moderate to severe symptoms of depression, a new study suggests.

For many of these patients — particularly those with severe symptoms — depression occurs in a toxic blend of high levels of anxiety, traumatic stress, impaired day-to-day functioning and significant pain and other physical symptoms, findings published in the journal Lung Cancer showed.

“The results suggest doctors need to screen lung cancer patients for depression and then act to refer patients for care,” said study lead author Barbara Andersen from the Ohio State University in the US.

“Some oncologists may have a mindset that ‘of course, you’re depressed, you have lung cancer.’ This may show an under-appreciation of the breadth of depressive symptoms and other difficulties which accompany it,” Andersen said.

Depression
In such patients, depression occurs in a toxic blend of high levels of anxiety and traumatic stress. Lifetime Stock

Patients with moderate or severe depressive symptoms are more likely to have lower quality of life and worse disease outcomes compared to those also diagnosed with lung cancer but with mild or no depressive symptoms.

According to the researchers, data came from 186 patients at one cancer hospital who had been recently diagnosed with advanced-stage non-small cell lung cancer, which accounts for 85 per cent of all lung cancer cases.

Patients completed a telephone survey measuring psychological and physical symptoms, stress and day-to-day functioning.

Results showed that eight per cent of the patients scored at the severe depressive symptom level and 28 per cent had moderate depressive symptoms.

Nearly all (93 per cent) of the patients with severe depression said the depressive symptoms made it difficult to do their work, take care of things at home and get along with other people.

Compared to other cancer patients, those with high levels of depressive symptoms were much more likely to report severe physical symptoms, including 73 per cent who said they experienced ‘quite a bit’ or ‘very much’ pain.

Depression in patients
Patients with moderate or severe level of depression are more likely to have lower quality of life. Lifetime Stock

Every one of the patients with severe depressive symptoms said they had severe or moderate issues functioning with their usual activities such as work, study, housework and family or leisure activities.

In general, those with moderate depressive symptoms saw negative effects that were somewhat less — but still significant — than those with severe symptoms, the study found.

But there were two striking differences between the groups.

One was in the severity of generalised anxiety disorder (or GAD) symptoms, the most common anxiety disorder.

About 11 per cent of those with moderate depressive symptoms had moderate to severe GAD, compared to 73 per cent of patients with severe depressive symptoms.

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Second, many fewer of the patients with moderate depressive symptoms had impairments in self care (eight per cent versus 33 per cent in those with severe depressive symptoms), mobility (33 per cent versus 73 per cent) and usual activities (38 per cent versus 100 per cent). (IANS)