• Lung cancer is the number one cause of cancer deaths in both men and women in the U.S. and worldwide.
• Cigarette smoking is the principal risk factor for development of lung cancer.
• Passive exposure to tobacco smoke also can cause lung cancer.
• The two types of lung cancer, which grow and spread differently, are the small cell lung cancers (SCLC) and non-small cell lung cancers (NSCLC).
• The stage of lung cancer refers to the extent to which the cancer has spread in the body
• Treatment of lung cancer can involve a combination of surgery, chemotherapy, and radiation therapy as well as newer experimental methods.
• The general prognosis of lung cancer is poor because doctors tend not to find the disease until it is at an advanced stage. Five-year survival is 40%-50% for early stage lung cancer, but only 1%-5% in advanced, inoperable lung cancer.
• Smoking cessation is the most important measure that can prevent the development of lung cancer.

Cancer of the lung, like all cancers, results from an abnormality in the body's basic unit of life, the cell. Normally, the body maintains a system of checks and balances on cell growth so that cells divide to produce new cells only when new cells are needed. Disruption of this system of checks and balances on cell growth results in an uncontrolled division and proliferation of cells that eventually forms a mass known as a tumor.