Lung cancer is the uncontrolled growth of abnormal cells in one or both lungs. These abnormal cells do not carry out the functions of normal cells and do not develop into healthy lung tissue. As they grow, the abnormal cells can form tumors and impede the function of the lung, which is to provide oxygen to the body via the blood.

There are two main types of lung cancer, non-small cell lung cancer and small cell lung cancer. These names refer to how the cancers look under a microscope to a pathologist.

Most cancers are non-small cell. There are subtypes of non-small cell lung cancer. Because different types of lung cancer are treated differently, your oncologist will determine exactly what treatment is best for you.

By far, the most important risk for lung cancer is smoking tobacco. Nearly 87% of all lung cancers in the United States are smoking-related. Quitting smoking helps to reduce that risk.

Exposure to secondhand smoke also increases the risk of lung cancer. According to the 2006 Surgeon General's Report on the effects of secondhand smoke, nonsmokers exposed to secondhand smoke at home or at work increase their risk of developing lung cancer by 20 percent to 30 percent. Secondhand smoke also increases the risk of heart disease and other ailments.

*Sources: From LungCancer.org, http://www.lungcancer.org/reading/