Risk Factor of Lung Cancer

The major cause of lung cancer is cigarette smoking, representing 85 to 90 percent of all cases. Lung cancer is predominantly a disease of the elderly; almost 70% of people diagnosed with lung cancer are over 65 years of age. It is rare in people under age 45.

One of the reasons to cause lung cancer is being a passive smoker or "secondhand" smoker. Passive smoking or the inhalation of tobacco smoke by nonsmokers, who share living or working quarters with smokers, also is an established risk factor for the development of lung cancer. Research has shown that nonsmokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with nonsmokers who do not reside with a smoker.

Radon gas is the second leading cause of lung cancer and is found naturally in soil and rocks. Radon gas is a natural, chemically inert gas that is a natural decay product of uranium. Uranium decays to form products, including radon, that emit a type of radiation. As with asbestos exposure, concomitant smoking greatly increases the risk of lung cancer with radon exposure. Radon gas can travel up through soil and enter homes through gaps in the foundation, pipes, drains, or other openings. Homeowners can purchase radon kits to test whether the gas exists in their home. If it does, measures can be taken to eliminate it. They stick to the lining of the lungs when these fibers are inhaled, which may eventually lead to lung cancer.

Besides, Carcinogens are a class of substances that directly damaging DNA, promoting or aiding cancer. Tobacco, asbestos, arsenic, radiation such as gamma and x-rays, the sun, and compounds in car exhaust fumes are all examples of carcinogens. Free radicals are formed that try to steal electrons from other molecules in the body when our bodies are exposed to carcinogens. These free radicals damage cells and affect their ability to function and divide normally. About 87% of lung cancers are related to smoking and inhaling the carcinogens in tobacco smoke. Even exposure to second-hand smoke can damage cells so that cancer forms.

Cancer can be the result of a genetic predisposition that is inherited from family members, such as individual genetic susceptibility, may play a role in the causation of lung cancer. It is possible to be born with certain genetic mutations or a fault in a gene that makes one have a chance to develop cancer later in life. Numerous studies have shown that lung cancer is more likely to occur in both smoking and nonsmoking relatives of those who have had lung cancer than in the general population. Recently, the largest genetic study of lung cancer ever conducted, involving over 10,000 people from 18 countries and led by the International Agency for Research on Cancer (IARC), identified a small region in the genome (DNA) that contains genes that appear to confer an increased susceptibility to lung cancer in smokers.

Air pollution from vehicles, industry, and power plants can raise the likelihood of developing lung cancer in exposed individuals. Up to 1% of lung cancer deaths are attributable to breathing polluted air, and experts believe that extended exposure to highly polluted air can carry a risk for the development of lung cancer similar to that of passive smoking.

Risk factor of lung's cancer.