There are two major types of lung cancer, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Staging lung cancer is based on whether the cancer is local or has spread from the lungs to the lymph nodes or other organs. Because the lungs are large, tumors can grow in them for a long time before they are found. Even when symptoms—such as coughing and fatigue—do occur, people think they are due to other causes. For this reason, early-stage lung cancer (stages I and II) is difficult to detect.

Non-Small Cell Lung Cancer

Non-small cell lung cancer accounts for about 85 percent of lung cancers and includes:

• Adenocarcinoma, the most common form of lung cancer in the United States among both men and women;
• Squamous cell carcinoma, which accounts for 25 percent of all lung cancers;
• Large cell carcinoma, which accounts for about 10 percent of NSCLC tumors.

Once your lung cancer has been diagnosed, your doctor will work to determine the extent (stage) of your cancer. Your cancer’s stage helps you and your doctor decide what treatment is most appropriate.

Staging tests may include imaging procedures that allow your doctor to look for evidence that cancer has spread beyond your lungs. These tests include CT scans, magnetic resonance imaging (MRI), positron emission tomography (PET) and bone scans. Not every test is appropriate for every person, so talk with your doctor about which procedures are right for you.

Stages of lung cancer

• Stage I. Cancer is limited to the lung and hasn’t spread to the lymph nodes. The tumor is generally smaller than 2 inches (5 centimeters) across.
• Stage II. The tumor at this stage may have grown larger than 2 inches, or it may be a smaller tumor that involves nearby structures, such as the chest wall, the diaphragm or the lining around the lungs (pleura). Cancer may also have spread to the nearby lymph nodes.
• Stage III. The tumor at this stage may have grown very large and invaded other organs near the lungs. Or this stage may indicate a smaller tumor accompanied by cancer cells in lymph nodes farther away from the lungs.
• Stage IV. Cancer has spread beyond the affected lung to the other lung or to distant areas of the body.

Small cell lung cancer is sometimes described as being limited or extensive. Limited indicates cancer is limited to one lung. Extensive indicates cancer has spread beyond the one lung.