Researchers have found that a 20-a-day smoker will develop around 150 mutations in every lung cell each year, raising their risk of developing cancer. As reported by BBC News, an international group of scientists from the Wellcome Trust Sanger Institute and Los Alamos National Laboratory sequenced thousands of tumour genomes to find a direct link between the number of cigarettes a person smokes in a lifetime and the number of mutations in tumour DNA.  The mutations developed will last even if someone gives up smoking, and mutations were also commonly found in the larynx, mouth, bladder and liver along with the lungs. Joint lead author Professor Sir Mike Stratton from the Wellcome Trust Sanger Institute said: “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.” If you are looking to stop smoking, there is support available from NHS Smokefree as well as information and tips from charities such as ASH.