Share:
Cancer by pure chance? Anyone who has cancer is unlucky
Every year, around 14 million people worldwide contract cancer and around 8.8 million people die from it. Experts point out how important it is to maintain a healthy lifestyle to reduce your personal cancer risk. However, researchers now report that pitch plays a much greater role in the onset of the disease than previously thought.
Number of cancer diagnoses doubled in Germany
According to experts, around 14 million people worldwide contract cancer every year and around 8.8 million people die of it. In Germany, too, there are more and more new cases of cancer. The number of new diagnoses has almost doubled in this country since 1970. According to the Robert Koch Institute (RKI), every second German citizen will get sick sooner or later.
Researchers have found that for some types of cancer it depends to a large extent on chance, who is ill. A healthy lifestyle is nevertheless an important contribution to cancer prevention. (Image: liukovmaksym / fotolia.com) Many diseases could be avoided
A large proportion of all cancers are considered preventable. A healthy lifestyle can significantly reduce the risk of cancer. However, American scientists now report that people who develop cancer are often just unlucky.
That the genes and lifestyle play a role in whether someone has cancer, should be largely unchallenged. But also chance has a big influence here. And apparently a larger than previously thought.
According to an analysis by US researchers, two thirds of all cancer mutations are due to random stem cell division failure.
Two-thirds of cancers are due to DNA copying errors
As the scientists from the Johns Hopkins University in Baltimore report in the journal "Science", their study suggests that 66 percent of the mutations that cause cancer are due to DNA copying errors, 29 percent to environmental factors and 5 percent to hereditary mutations.
However, the composition of the three factors varies greatly from cancer to cancer. For tumors of the prostate, brain and bone, 95 percent of the mutations are due to random defects, and 77 percent in the case of the pancreas.
In lung cancer, on the other hand, environmental factors - especially smoking - determine about 65 percent of the mutations.
According to the authors, several mutations must come together before a tumor arises. Much of the DNA changes have no consequences.
Avoid smoking
But it is not doubted that about 40 percent of all cancer cases are preventable. "Our studies do not contradict classical epidemiology, they rather complement it," reports the team.
"It is well-known that we need to avoid environmental factors such as smoking to reduce the risk of cancer," said biostatist Cristian Tomasetti in a statement from his university.
"It is less well known that a normal cell that divides and copies its DNA makes several mistakes each time," says the scientist.
Patients are not always to blame for their illness
Already two years ago a publication of the same researchers had provided much discussion. One of the main criticisms at the time was that the influence of random mutations had become too prominent.
In addition, the authors were accused of methodological errors. At that time, only data from the US and common cancers such as breast or prostate cancer were included.
The current study now provides figures on the incidence of 32 different cancers from 69 countries, which make up two-thirds of the world's population.
Some cancers can occur, "no matter how perfect the environment is," said oncologist Bert Vogelstein.
For patients who develop cancer despite a healthy lifestyle, this could be a small consolation. "It's not her fault," said the doctor. "There is nothing behind the disease that you did or did not do."
Two forms of cancer prevention
The study authors recommend two forms of cancer prevention: For types of tumors in which the environment plays an important role, one should give tips for prevention. In the case of tumors, which depend in particular on chance, good early detection is required.
When it comes to cancer prevention measures, it is above all the fight against smoking.
Another way to reduce your personal cancer risk is to limit your alcohol intake. After all, alcohol can trigger seven different types of cancer, according to scientific findings.
Furthermore, it is recommended to pay attention to a healthy diet, to exercise regularly and to avoid overweight. The latter, according to a recent study, increases the risks of 11 cancer diseases.
Most mutations probably do not matter
"An understanding of cancer risk, which would ignore bad luck, would be inappropriate as well as one that would not take into account environmental and genetic factors," said Martin Nowak of Harvard University in a "Science" commentary.
"The first analysis by Tomasetti and Vogelstein has already caused much debate, and the new results will do the same. The results show a clear need to understand cancer mathematically precise. "
Andreas Trumpp from the German Cancer Research Center (DKFZ) in Heidelberg sees this obviously similar. "Mathematically, we do not yet understand the development of a tumor in detail," explained the expert, according to a news agency dpa. "The data is too thin for that."
However, the study indicates that the number of stem cell divisions strongly influences cancer risk. "The vast majority of mutations probably do not matter," says Trumpp.
"But if the mutation of a stem cell affects an important gene, it may be passed on to billions of offspring for life and may be the seed of a cancer."
Ultimately it depends on the type of tumor, how large the role of environment, genetic factors and cell divisions. (Ad)