The average survival time of patents with untreated carcinoma of the bronchus is 9 months. The three of the most damaging toxins are nicotine, tars, and carbon monoxide. Second-hand smoke inhaled by both smokers and nonsmokers is another important cause of lung cancer. Smokers that inhale two or more packs of cigarettes a day, have a cancer mortality rate 12-25 times greater than a nonsmokers. The risk of lung cancer falls dramatically within a couple years if smoking is stopped.
Radon is the second leading cause of lung cancer.
It is a radioactive gas found in the earth's rocks and soil, formed by the natural breakdown of radium. Excessive exposure of radon in the home may increase the risk of lung cancer especially in smokers. If the radon levels are found to be to high, remedial actions should be taken. Another cause of cancer is on the job exposure to carcinogens. The best known carcinogen is asbestos.