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Smoking causes DNA mutations

A 20-a-day habit creates genetic changes in lung and larynx cells

Mark Gould

Friday, 04 November 2016

A person smoking 20 cigarettes a day develops hundreds of permanent mutations in cells in the lung, larynx and mouth each year according to new research.*

The researchers, an international group including the Wellcome Trust Sanger Institute in Cambridgeshire and the Los Alamos National Laboratory in New Mexico, writing in the journal Science, say analysing tumour DNA may help explain the underlying causes of other cancers. There are 35,000 deaths a year in the UK from lung cancer, and it is estimated that nine out of 10 cases are preventable.

The researchers said that in tissues such as the lung, which are directly exposed to smoke, they could find the mutational signature of the chemicals in tobacco smoke, of which at least 60 are carcinogens. However, they could not find this same pattern in tissues such as the bladder, which are not directly exposed.

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."

Prof Stratton said in these organs smoking seemed to be accelerating a natural mutational process, but how it did this was "mysterious and complex".

He said the same investigative approach could be used with other cancers where the underlying causes were less well understood.

"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," he said.

* Stratton MR, et al. Mutational signatures associated with tobacco smoking in human cancer. Science 04 Nov 2016, Vol. 354, Issue 6312, pp. 618-622. DOI: 10.1126/science.aag0299

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