Lung cancer is one of the most common forms of cancer in the world and is a leading cause of death for both men and women in the U.S. Early detection is key. Newer screenings are detecting more early cancers than ever before and helping to save lives.
What is Lung Cancer?
Lung cancer is the uncontrolled growth of abnormal cells that begins in one or both lungs, usually in the cells lining the air passages. When you breathe, air goes through your nose, down your windpipe (trachea), and into the lungs, where it spreads through tubes called bronchi. Most lung cancer begins in the cells that line these tubes.
It is more common in older adults and rare in people under age 45.
Types of Lung Cancer
There are two main types of lung cancer:
- Small cell lung cancer: Small cell lung cancer makes up about 20 percent of all lung cancer cases. It spreads much more quickly than non-small cell lung cancer. There are two different types of small cell lung cancer.
- Small cell carcinoma (oat cell cancer)
- Combined small cell carcinoma
- Non-small cell lung cancer: Non-small cell lung cancer is the most common form of the disease and usually grows and spreads more slowly than small cell lung cancer. There are three forms of non-small cell lung cancer.
- Adenocarcinomas are often found in an outer area of the lung
- Squamous cell carcinomas are usually found in the center of the lung next to an air tube (bronchus)
- Large cell carcinomas can occur in any part of the lung. They tend to grow and spread faster than the other two types.
If the lung cancer is made up of both types, it is called mixed small cell/large cell cancer.
Stages of Lung Cancer
Non-small cell lung cancers are assigned a stage from I to IV in order of severity:
- In stage I, the cancer is confined to the lung.
- In stages II and III, the cancer is confined to the lung and, possibly, the lymph nodes.
- Stage IV cancer has spread outside of the lung to other parts of the body.
Small cell lung cancers are staged using a two-tiered system:
- Limited stage small cell lung cancer is confined to its area of origin in the lung and lymph nodes.
- Extensive-stage small cell lung cancer has spread beyond the lung to other parts of the body.
While primary lung cancer originates in the lungs, secondary lung cancer starts elsewhere in the body, metastasizes and eventually reaches the lungs. They are considered different types of cancers and require different forms of treatment. If the cancer started somewhere else in the body and spread to the lungs, it is called metastatic cancer to the lung.
Learn More about Lung Cancer
Risk Factors and Prevention of Lung Cancer
Lung Cancer Tests and Diagnosis
Treatment of Lung Cancer