Certain genes could increase the risk of lung cancer in a smoker, new evidence suggests.
Three "letter changes" from genetic codes occurred more often in lung cancer patients, scientists revealed. They scanned the genetic codes of more than 7,000 people.
The risk of lung cancer in current or former smokers who had two copies of each variant in their genes rose by 80%, while those who had only one copy of each had a 28% higher risk.
Non-smokers who also had the variants were not affected the same way.
Scientists said that the variations are found in a gene family that influences smoking and tobacco consumption, besides affecting the growth and death of cells.
Professor Richard Houlston, study leader from the Institute of Cancer Research in London and Surrey, said: "This research confirms work done at the ICR and elsewhere that has previously implicated these areas in lung cancer risk and the type that develops."
Dr Lesley Walker, director of cancer information at Cancer Research UK, which funded the study, said: "This research shows that inherited genetic variation accounts for some of this risk and the type of lung cancer that develops."