Lung cancer patients who never smoked have tumors that show greater genomic instability, researchers in Canada said. Principal investigator Kelsie Thu of the BC Cancer Agency Research Center in Vancouver says as many as 25 percent of lung cancer cases worldwide occur in people who have never smoked, and these patients typically exhibit traits different from those of smokers. They are more often women, Asian, have a higher incidence of epidermal growth factor receptor mutations, better responses to EGFR-targeting drugs and are more commonly diagnosed with adenocarcinoma, Thu said. \"We identified several genomic regions that were differentially altered in the lung tumor genomes of smokers and never smokers,\" Thu said in a statement. \"We also found that a greater fraction of lung tumor DNA harbored genetic alterations in never smokers compared to smokers. The discovery that there are different patterns of genetic alterations in smokers and never smokers suggests that lung cancers in these cohorts are likely distinct diseases driven by different molecular mechanisms, and thus, may require different treatments.\" The findings were presented at the 14th World Conference on Lung Cancer in Amsterdam.