While cigarette smoking is an undisputed cause of lung cancer, not all cases of lung canceroccur in smokers or former smokers. Each year, over 170,000 Americans develop lung cancer, and approximately ten per cent of lung cancers, or 17,000 cases, occur in non-smokers. Although not every non-smoker suffering from lung cancer will have an identifiable risk factor for development of the disease, a number of conditions and circumstances have been identified that will increase a non-smoker’s chance of developing lung cancer.
- Passive smoking, or the inhalation of tobacco smoke from other smokers sharing living or working quarters, is an established risk factor for the development of lung cancer. Non-smokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with other non-smokers. Each year, up to 3,000 lung cancer deaths are estimated to occur in the U.S. that are attributable to passive smoking.