Most cases of cancer down to bad luck rather than lifestyle or inherited genes

Pancreatic cancer cells dividing. Random mutations in DNA are behind two thirds of adult cancers, a study says. Photograph: Visuals Unlimited, Inc./Dr. Stan/Getty Images/Visuals Unlimited

Most cases of cancer are largely the result of bad luck rather than unhealthy lifestyles, diet or inherited genes, new research suggests.

Random mutations that occur in DNA when cells divide are largely responsible for two thirds of adult cancers across a wide range of tissues.

The remaining third are linked to environmental factors or defective inherited genes.

But the scientists warn that poor lifestyle can add to the bad luck factor involved in cancer.

The researchers analysed published data on the number of divisions of self-renewing stem cells that occur in an average lifetime in 31 different tissues.

These results were compared with the lifetime incidence of cancer in the same tissues.

A strong correlation was seen between a particular tissues stem cell division rate and its likelihood of developing cancer.

The more often cells divide, the more likely it is that letters of their genetic code will become jumbled, leading to an increased cancer risk.

Overall, the study found that random mutations due to stem cell division could largely explain around 65% of cancer incidence.

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Most cases of cancer down to bad luck rather than lifestyle or inherited genes