Most cancers are 'bad luck'

When a dividing cell copies DNA, enzymes ‘proof read’ the new strands to make sure they carry the same genetic code as the original. Considering our cells divide trillions of times, the numerous processes to check and repair mistakes in the genetic code make remarkably few errors. But sometimes these quality control mechanisms miss a mutation. Now a new study using a sophisticated mathematical model suggest that these random DNA copying errors cause two-thirds of cancers – with lung cancer being a notable exception.

The authors looked at 32 malignancies and calculated that environmental factors account for 29% of the mutations in cancers in the UK. Inherited genes accounted for 5% of the mutations. Random copying errors accounted for the remaining 66% of mutations driving cancers.