Content Summary : Lung Cancer © copyright 2004 U-M Comprehensive Cancer Center The University of Michigan Health System web site does not provide specific medical advice and does not endorse any medical or professional service obtained through information provided on this site or any links to this site. Use of the UMHS web site does not replace medical consultation with a qualified health or medical professional to meet the health and medical needs of you or others. While the content of the UMHS web site is frequently updated, medical information changes rapidly and therefore, some information may be out of date, and/or contain inaccuracies or typographical errors. Lung cancer is an abnormal growth of cells in the lungs. Your 2 lungs take up most of the space in your chest. They breathe in oxygen needed by your body and breathe out carbon dioxide, which is a waste product. Lung cancer can spread to other parts of the body, most often to the liver, brain, bones, and other parts of the lungs, including the outer lining (called the pleura). Cancer from other parts of the body may also spread to the lungs, but this is not called lung cancer. Lung cancer is one of the most common forms of cancer in the US and a leading cause of cancer deaths in both men and women. How does it occur? Tobacco is linked to most cases of lung cancer. In addition to smoking, factors that increase your risk for lung cancer include exposures to: • other people's smoke (secondhand smoke, or passive smoking) • air pollution • radiation at your job, for medical exams, or in your environment • asbestos • radon gas • industrial chemicals such as the byproducts from petroleum refining.