‘Bad luck’ mutations increase cancer risk more than behaviour, study says

For the first time, researchers have estimated what percentage of cancer mutations are due to environmental and lifestyle factors, hereditary factors and random chance. Overall, 66% of the genetic mutations that develop into cancer are caused by simple random errors occurring when cells replace themselves, according to a new study published in the journal Science.

Environmental factors contribute 29% of mutations, while the remaining 5% are inherited, say Cristian Tomasetti and Dr. Bert Vogelstein, both of Johns Hopkins University.

In a previous paper, Tomasetti and Vogelstein asserted that your risk of developing cancer is largely based on random DNA errors that occur when self-renewing cells divide.

In their new paper, they offer more detail describing how dumb luck plays a more significant role than either environmental, lifestyle or hereditary factors in causing this disease.

“Every time a perfectly normal cell divides, as you all know, it makes several mistakes — mutations,” explained Vogelstein in a briefing. “Now most of the time, these mutations don’t do any harm. They occur in junk DNA, genes unrelated to cancer, unimportant places with respect to cancer. That’s the usual situation and that’s good luck.” Occasionally, one of these random miscopies will occur in a cancer driving gene. “That’s bad luck,” said Vogelstein.