lung and airway disorders
Lung Cancer
Causes of Lung Cancer
Cigarette smoking is the leading cause of lung cancer, accounting for about 85% of all lung cancer cases. The risk of developing lung cancer varies by both the number of cigarettes smoked and the number of years of smoking. Still, some heavy smokers do not develop lung cancer. In people who quit smoking, the risk of developing lung cancer decreases, but former smokers continue to have a higher risk of developing lung cancer than people who never smoked. About 15 to 20% of people who develop lung cancer have never smoked or have smoked only minimally. In these people, the reason why they develop lung cancer is unknown, but certain genetic mutations may be responsible. Other possible risk factors include Air pollution Exposure to cigar smoke Exposure to secondhand cigarette smoke Exposure to carcinogens such as asbestos, radiation, radon, arsenic, chromates, nickel, chloromethyl ethers, polycyclic aromatic hydrocarbons, mustard gas, or coke-oven emissions that are encountered or breathed in at work Exclusively using open fires for cooking and heating The risk of contracting lung cancer is greater in people who are exposed to these substances and who also smoke cigarettes. The risk of lung cancer related to electronicnicotinedelivery systems such as e-cigarettes remains to be determined, although doctors think that the substances created by burning tobacco are more likely to be the cause of cancer thannicotineitself. It is unknown whether marijuana smoking increases the risk of lung cancer. Whether and how much an exposure to household radon increases risk of lung cancer is controversial. However, many reports suggest that radon exposure is a risk factor for lung cancer. In rare incidences, lung cancers, especially adenocarcinoma and bronchioloalveolar cell carcinoma (a type of adenocarcinoma also known as adenocarcinoma in situ), develop in people whose lungs have been scarred by other lung disorders, such as Tuberculosis (TB) Also, smokers who take beta-carotene supplements may have an increased risk of developing lung cancer. Although smoking causes most cases, people who have never smoked may still get lung cancer. 