Patients with lung cancer often do not develop symptoms until the cancer is in an advanced stage. The actual time from when one cell becomes cancerous until it is large enough to be diagnosed or produce symptoms may take as long as 10 to 40 years. Eighty percent of lung cancers are due to tobacco smoke. There are over 2,000 known cancer-causing chemicals in tobacco smoke. Other well established carcinogens of the lung include radon, asbestos, bischolomethylether, nickel, chromates, coal tar, copper radioactive materials and arsenic.
Many occupations have an increased risk for developing lung cancer.
For example, asbestos insulation workers have 92 times the risk of developing of lung cancer, and smelter workers have 3-8 times the risk of developing lung cancer. The risk of lung cancer is also increased in people who work in the manufacturing of certain industrial gases, pharmaceuticals, soaps and detergents, paints, inorganic pigments, plastics, and synthetic rubber. The risk of developing lung cancer is related to the amount of exposure to the cancer causing agent. For example, the risk of lung cancer in humans is proportional to the number of cigarettes smoked. The risk of developing lung cancer is 8-20 times greater in smokers compared to people who have never smoked.