Lung cancer is a unique disease in that the tobacco industry is its cause. more than 85% of lung cancers are caused by active or passive smoking. According to the Surgeon General’s report, both active and passive smoking can cause lung cancer. This causal relationship between active smoking and lung cancer is also found in other tumors, such as esophageal, oral cavity, larynx and pharynx cancers. Smoking can damage almost every organ in the body. People who live with smokers have a 20 to 30 percent increased risk of developing lung cancer. Tobacco also contains the highly addictive substance nicotine, which further complicates the problem. Oncologists should actively encourage their patients to quit smoking, especially in cancer patients. Programs through behavior change and the combined use of smoking cessation medications [drugs already approved by the U.S. Food and Drug Administration (FDA)] are useful for quitting smoking. Radon gas, a decay product of 226 radium, is radioactive and is the second leading cause of lung cancer development. The decay of this isotope can produce substances that release alpha particles, which can destroy cells and thus increase the likelihood of cellular malignancy. Asbestos is a known carcinogenic inorganic compound that can split into airborne fragments, and exposure to airborne asbestos fibers increases the risk of lung cancer in people, especially those who smoke. It is estimated that about 3 to 4 percent of lung cancer cases are due to exposure to asbestos. In addition, other possible risk factors include recurrent lung infections, tuberculosis secondary to scar formation, family history, and exposure to other carcinogens such as bis(chloromethyl)ether, polycyclic aromatic hydrocarbons, chromium, nickel, and organic arsenic compounds.