Smoking causes DNA changes, scientists find

A study published in the journal Science has outlined that smoking causes hundreds of DNA mutations, which are permanent and can persist even if the smoker quite the habit.

The researchers sequenced thousands of tumour genomes, and found a 20-a-day smoker would rack up an average of 150 mutations in every lung cell each year.

The analysis highlighted a direct link between the number of cigarettes smoked in a lifetime and the number of mutations in tumour DNA.

It found that on average, smoking a packet of cigarettes a day led to: 150 mutations in each lung cell every year; 97 in the larynx or voice box; 23 in the mouth; 18 in the bladder; and six in the liver.

Joint lead author Prof Sir Mike Stratton, from the Wellcome Trust Sanger Institute, said: "The more mutations there are, the higher the chance that these will occur in the key genes that we call cancer genes, which convert a normal cell into a cancer cell."

“By looking in the genomes of the cancers, we will find the archaeological traces of past exposures which have been responsible for generating the cancers and that may potentially lead to prevention.”

Dr David Gilligan, consultant oncologist at Papworth Hospital and Roy Castle Lung Foundation trustee, said: "For every 150 mutations in the cell each year, that is 150 opportunities for lung cancer to develop.

"Lung cancer has been at the bottom of the survival league for many years, but there are many exciting developments, including immunotherapy and genetically targeted drug treatments."