US scientists claim that up to 90% of cancer risk comes from external factors.

Published on December 16 in the journal Nature, scientific work from specialists from the University of New York at Stony Brook attributes most of the causes of cancer in humans to external factors. According to researchers, the contribution of internal factors (features of functioning of the body) to the risk of cancer is no more than 10-30%.

Scientists have used several ways to study stem cell division. It is possible errors in this process lead to the appearance of tumors. Researchers have conducted stem cell experiments, computer simulations, and molecular studies of tumor tissues.
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Studying stem cell division, scientists expected that the tissues with similar models of cell division and the risk of a malignant tumor will also be the same. But this was not the case, which allows to conclude that the external factors have a strong influence on the risk of cancer. The researchers also confirmed that according to statistics, people moving from places with a good environmental situation to places where the environment increases the risk of cancer, and the risk of getting sick is actually increasing.

In January 2015, a study on the same topic made a lot of noise in the media, because its authors came to the conclusion that 2/3 of the contribution to an increase in the risk of oncology is made by internal factors. Or, as they themselves put it, “failure” - because of the constant division of the cells of the body, the likelihood of the appearance of cancer cells increases.

But the authors of the current study reject such conclusions. “You can't blame everything for failure,” said Yusuf Hannun, head of the university at Stony Brook. - You can not smoke, and at the same time write off the occurrence of cancer to failure.

Yusuf compares this situation with the "Russian roulette". Of course, one cartridge in the drum gives the game a risk, but if a person smokes or in other ways increases this risk, he actually adds cartridges to the drum.

Virtually none of the scientists does not deny the influence of external factors on the risk of cancer. Smoking, unhealthy lifestyle, poor diet, poor environmental conditions in the place of residence - all this adds risks.

But scientists are still unable to agree on the proportions in which the internal and external factors influence the risk of cancer. And although the search for drugs for this disease goes without a full understanding of the reasons for its occurrence, this understanding could make an undeniable contribution to the fight against it.