Cancers are diseases that involve the uncontrolled growth and dividing of cells in the body. These cancerous cells can form solid masses of tissue called tumors. The uncontrolled cell growth of cancer disrupts the activity of normal cells and systems in the body.
Lung cancer is a cancer that occurs in the lungs. There are two main types of lung cancer:
- Non-small cell lung cancer: is the most common type of lung cancer. Some of the sub-types of non-small cell lung cancer are squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. Each of these sub-types of non-small cell lung cancer begins in a different type of cell in the lungs. Each sub-type can grow and spread in different ways.
- Small-cell lung cancer: is less common than non-small cell lung cancer. Some of the sub-types of small-cell lung cancer are small-cell carcinoma and combined small-cell carcinoma.
Most lung cancers are caused by smoking. The risk of lung cancer increases the longer a person smokes. However, once a person stops smoking, the risk of lung cancer decreases as time passes.