Most types of cancer can be put down to bad luck rather than risk factors such as smoking, a study has suggested.
A US team were trying to explain why some tissues were millions of times more vulnerable to cancer than others.
The results, in the journal Science, showed two thirds of the cancer types analysed were caused just by chance mutations rather than lifestyle.
However some of the most common and deadly cancers are still heavily influenced by lifestyle.
And Cancer Research UK said a healthy lifestyle would still heavily stack the odds in a person’s favour.