About one fourth of the newly diagnosed lung cancer cases are small cell carcinomas - a type of lung cancer in which the cells are small and round. This type of cancer grows rapidly and quickly spreads to other organs. If you do smoke, quitting early in life is best, but it is never too late to kick the habit and reduce your risk. Follow safety rules and procedures to reduce exposure to carcinogens in the workplace. By far, smoking tobacco causes most lung cancers.
Tobacco smoke has many carcinogens - substances that damage cells.
The risk of lung cancer begins to slowly decrease as soon as a person quits smoking. Although smoking is without question, the major cause of lung cancer, there are some other causes as well. Passive smoking is one. Exposure to other carcinogens, such as asbestos, is another. Exposure to high levels of radon may also increase the risk - especially for smokers.