DNA 'typos' may cause 66% of cancer mutations

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Tomasetti and Bert Vogelstein, the co-director of the Ludwig Center at the Johns Hopkins Kimmel Cancer Center, previously reported in 2015 how random genetic mutations could explain why certain cancers in the USA are far more prevalent than others, such as colon cancer vs brain cancer. Say a cancer develops if a cell acquires three specific mutations: two of those mutations could be random and the third could be induced by some toxic chemical in air pollution.

"We hope that this research offers comfort to the literally millions of patients who have developed cancer but who have led near-perfect lifestyles, who haven't smoked, who avoided the sun without sunscreen, who eat perfectly healthy diets, who exercised regularly", Vogelstein said, adding that he hopes it will also be reassuring to parents of children with cancer.

In lung cancer, they noted, 65% of all the mutations were due to environmental factors, mostly smoking, and 35% were a result of DNA copying errors. "We now know as a result of this research that most of the enemies [in the war on cancer] are inside us". These factors can, in fact, cause cancer, but the third cause, random mutations, accounts for two-thirds of the disease.

Even with the best health intentions, cancer may still develop due to mistakes that crop up when cells divide to form new cells. They occur in junk DNA, genes unrelated to cancer, unimportant places with respect to cancer. There was a strong correlation between the lifetime risk of many types of cancers, such as those in the breast, prostate, kidney, and bone, and the number of stem cell divisions in those tissues.

However, the study's findings give researchers new information on how to tackle cancer prevention and treatment.

Yusuf Hannun, director of the Stony Brook Cancer Center in NY, worries that the study underestimates the contributions of environmental and heritable factors because researchers do not yet know how to fully predict these on the basis of sequence and epidemiological data. "It seems to make sense-the more divisions in stem cells, the more random mutations, the more cancer", Tomasetti said in the press conference. Dr Brawley believed that whilst the study has upset people who believed in cancer prevention and minimizing their risk through healthy living, it also helped provide an explanation to cancer sufferers who "had done everything right". But there's one really important distinction: cancers can be caused by several mutations.

For lay people, the takeaway message is that many cases of cancer can be prevented, even though many cancerous mutations cannot.

Their study set out to compare the number of stem cell divisions with cancer incidence around the world.

CANCER GENETICIST BERT VOGELSTEIN, on the need to detect cancer early in order to increase the chances of effectively treating the disease should such random mutations occur.

The "Why me?" reaction that can come after a cancer diagnosis may have no easy answer, with new research showing that most tumors are caused by random genetic "mistakes". They likened their results to a auto trip: the longer the drive, the higher the risk of being involved in an accident; the more your cells divide, the higher the risk of an unpredictable, cancer-causing error.

Live Science reported that a new study found most cancer cases to be caused by very random mistakes in a person's DNA. Vogelstein, for instance, said that the study does not contradict the generally-accepted wisdom that most cases of lung cancer cases are preventable.

She said that environmental causes of cancer have always been underestimated, and that estimates on their contribution to cancer will increase as more is learned. "An understanding of cancer risk that did not take bad luck into account would be as inappropriate as one that did not take environmental or hereditary factors into account", they conclude.

"Basically, this shows that cancer, to a certain extent, can be thought of as a side effect of evolution", said Vogelstein.

Though we can't predict how random mutations will cause cancer, knowing what we don't know is a marked improvement from swimming in unknown unknowns.