What Causes Lung Cancer
Smoking is the number one cause of lung cancer. Lung cancer may also be the most tragic cancer because in most cases, it might have been prevented -- 87% of lung cancer cases are caused by smoking. Cigarette smoke contains more than 4,000 different chemicals, many of which are proven cancer-causing substances, or carcinogens. Smoking cigars or pipes also increases the risk of lung cancer.
The more time and quantity you smoke, the greater your risk of lung cancer. But if you stop smoking, the risk of lung cancer decreases each year as normal cells replace abnormal cells. After ten years, the risk drops to a level that is one-third to one-half of the risk for people who continue to smoke. In addition, quitting smoking greatly reduces the risk of developing other smoking-related diseases, such as heart disease, stroke, emphysema and chronic bronchitis.
Many of the chemicals in tobacco smoke also affect the nonsmoker inhaling the smoke, making "secondhand smoking" another important cause of lung cancer. It is responsible for approximately 3,000 lung cancer deaths annually.
Radon is considered to be the second leading cause of lung cancer in the U.S. today. Radon gas can come up through the soil under a home or building and enter through gaps and cracks in the foundation or insulation, as well as through pipes, drains, walls or other openings. Radon causes between 15,000 and 22,000 lung cancer deaths each year in the United States -- 12 percent of all lung cancer deaths are linked to radon.
Radon problems have been found in every state. The EPA estimates that nearly 1 out of every 15 homes in the U.S. has indoor radon levels at or above the level at which homeowners should take action -- 4 picocuries per liter of air (pCi/L) on a yearly average. Radon can be a problem in schools and workplaces, too.
Because you cannot see or smell radon, the only way to tell if you are being exposed to the gas is by measuring radon levels. Exposure to radon in combination with cigarette smoking greatly increases the risk of lung cancer. That means for smokers, exposure to radon is an even greater health risk.
Another leading cause of lung cancer is on-the-job exposure to cancer-causing substances or carcinogens. Asbestos is a well-known, work-related substance that can cause lung cancer, but there are many others, including uranium, arsenic, and certain petroleum products.
There are many different jobs that may involve exposure. Some examples are working with certain types of insulation, working in coke ovens, and repairing brakes. When exposure to job-related carcinogens is combined with smoking, the risk of getting lung cancer is sharply increased.
A recent study published in the Journal of American Medical Association suggests that particulate matter pollution can cause lung cancer.
Lung cancer takes many years to develop. But changes in the lung can begin almost as soon as a person is exposed to cancer-causing substances. Soon after exposure begins, a few abnormal cells may appear in the lining of the bronchi (the main breathing tubes). If a person continues to be exposed to the cancer-causing substance, more abnormal cells will appear. These cells may be on their way to becoming cancerous and forming a tumor.
What Causes Lung Cancer
