The scientists say that while external factors are catalysts, one needs to have genetic defects to actually get the cancer
Studies have always attributed external factors behind cancer. A 2016 report by the World Health Organisation said, “Tobacco use, excessive alcohol use, unhealthy diet and physical inactivity are other lifestyle-related factors.”
However, a new study suggests that 66 per cent of cancers are caused by a genetic defect, rather than external factors. “The vast majority of cancers are just a mistake, an error in DNA replication, researchers say. In this way, developing cancer in many cases is unavoidable. Geneticist Bert Vogelstein and mathematician Cristian Tomasetti, at the Johns Hopkins Kimmel Cancer Center, conducted the study, a follow-up to an earlier one, which arrived at the same conclusion,” said a report in Science.
According to the study, every time cells divide, little mistakes in the copies of its DNA form. “Normally, they do not cause any trouble. But if it happens more than once in a gene that causes cancer, the disease can take root and the cell turns cancerous,” the study suggests.
The researchers found that these percentages vary from cancer to cancer. In some lung tumours, for example, environmental factors account for 65% of all cancer-causing mutations, whereas replication errors comprise only 35%. Yet in prostate, brain and bone cancers, more than 95% of cancer drivers are caused by random DNA-copying errors.
The research found that across 32 cancers indicated that about 66% of cancer-driving mutations are due to random DNA replication errors, with only 29% due to environmental factors and 5% to inherited mutations.
According to Vogelstein, the case for environmental factors may have been overemphasised. While speaking to Nature, he said, “If we think of the mutations as the enemies, and all the enemies are outside of our border, it’s obvious how to keep them from getting inside. But if a lot of the enemies — in this case close to two-thirds — are actually inside our borders, it means we need a completely different strategy.”
In addition, Vogelstein, while speaking to NPR added, "We're not saying the only thing that determines the seriousness of the cancer, or its aggressiveness, or its likelihood to cause the patient's death, are these mutations. We're simply saying that they are necessary to get the cancer."
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
 "cancer")
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
)
){kind=small}
){kind=small}
)
)
)
)
)
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}