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Researchers discover molecular fingerprints in smoking tumors
Smoking is harmful to health and can cause cancer - this is well known. Scientists from the USA and England have now investigated the genetic damage caused by the blue haze and came to a drastic result: tobacco smoke not only damages the lungs, but also leads to dangerous mutations in other organs.
150 mutations in each lung cell
Anyone who smokes a pack of cigarettes a day causes an average of 150 mutations in each lung cell each year. This is shown in a study published on Thursday in the science magazine, in which the cancer risk for smokers was examined. Researchers from the National Laboratory in Los Alamos (New Mexico, USA) and the Wellcome Trust Sanger Institute (Hinxton, England) had examined the genetic makeup of 5,000 tumors for the project. They compared those of smokers with those of people who had never smoked, according to the Wellcome Trust Sanger Institute.
The scientists discovered certain molecular fingerprints of DNA damage (“mutation signatures”) in the smoker's DNA in the genetic makeup of the tumors of smokers and counted how many of these special changes in the genetic makeup were found in the various tumors. It was shown that there is a direct connection between the number of mutations in the tumor DNA and the number of cigarettes smoked.
Genetic changes also in distant organs
The researchers identified the highest rates with around 150 mutations per cell in the lungs. In other parts of the body, too, tumors contained mutations that are associated with smoking. This explains, according to the message, how tobacco use causes different types of cancer. According to this, one pack of cigarettes a day in the year leads to an average of 97 mutations in every cell in the larynx. On average 39 changes in the pharynx and 23 in the mouth. Even organs such as the bladder and liver that have no direct contact with tobacco smoke are affected by the study with 18 and 6 mutations, respectively.
"This study offers new insights into how tobacco smoke causes cancer," says lead author Ludmil Alexandrow from the National Laboratory in a statement from his institute. “Our analysis shows that tobacco smoking causes mutations that lead to cancer through several different mechanisms. Smoking tobacco damages the DNA in organs that are directly exposed to smoke and also accelerates a variable cell clock in organs that are both directly and indirectly exposed to smoke, ”continued Alexandrow.
Study shows the need for preventive measures
According to the cancer expert Martina Pötschke-Langer from Heidelberg, the study reinforces existing knowledge. "But the application of knowledge must follow in politics and in parliament," the expert told the news agency "dpa". According to Pötschke-Langer, preventive measures such as an increase in the tobacco tax, a ban on advertising for tobacco products and stronger protection against non-smokers are necessary.
Tobacco smoke contains 7,000 chemicals
According to the study, tobacco smoke is a complex mixture of more than 7,000 chemicals, of which over 70 are known to cause cancer (carcinogens). Earlier epidemiological studies have linked smoking to an increased risk of 17 different types of cancer - including tumors in tissues that are not directly exposed to smoke. In the new study, the research team now identified more than 20 mutation signatures in these species and found a connection to cancer in five of them.
A signature, called "Signature 4", was primarily found in DNA that is damaged by direct exposure to tobacco smoke, such as the lungs. The “signature 5” was found for all types of cancer that are caused by smoking. According to the authors, other signatures would reinforce the theory that smoking increases the risk of multiple cancers by increasing the total number of mutations. However, the authors note that for some of the variants, the underlying mechanisms are still unclear.
Cancer caused by tobacco smoke is more complex than expected
“Our research shows that the way tobacco smoking causes cancer is more complex than we thought. In fact, we still don't fully understand the underlying causes of many types of cancer, ”said Mike Stratton of the Wellcome Trust Sanger Institute, according to his institute's announcement. "But this study on smoking tells us that looking at DNA in cancer can provide new, provocative clues as to how cancer develops and can be prevented," Stratton said.
From the point of view of the cancer expert Pötschke-Langer, the study is particularly important because of its scope: "This study will certainly attract a lot of attention," the former head of the Cancer Prevention Unit of the German Cancer Research Center (DKFZ) told the news agency.
Smoking is the greatest avoidable health risk
According to the Federal Ministry of Health, 28 percent of the adult population aged 18 and over smoke in Germany. Men smoke 31 percent more often than women (24 percent smoke). A clear decline can be observed among young people. In the past fifteen years, the proportion of 12 to 17 year olds who smoke has decreased from 27.5 percent in 2001 to 7.8 percent in 2015.
According to the ministry, around 120,000 people die each year from the consequences of tobacco use. This still represents the greatest avoidable health risk in Germany. A study recently showed, for example, that smoking significantly reduces the average life expectancy. Lung cancer deaths among women caused by smoking are also increasing dramatically.
Quitting smoking quickly brings positive effects
Taking cigarettes out of your own life is always a good idea - no matter how old you are. Quitting smoking primarily requires a firm will and consequent renunciation. But the success is quickly noticeable and the risk for most types of cancer drops significantly after just a few years as a non-smoker. (No)