Lung cancer is a disease that develops in lung tissues, especially in the lining of the airways. Non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) are the two most common types.
Learn more about the types of lung cancer.
NSCLC is the more common of the two, accounting for 80 to 85 percent of all lung cancers, according to the American Cancer Society (ACS).
How is lung cancer staged?
Doctors frequently classify the stages of NSCLC and SCLC using the TNM system, which involves the use of letters to denote lung tumor characteristics.
T (tumor): Has it spread to other organs or tissues nearby?
N (node): Has the cancer metastasized to nearby lymph nodes?
M (metastasis): Has the cancer metastasized to distant organs, such as the brain, bones, the other lung or other areas?
Although these classifications both use the TNM system, the actual stages of lung cancer will be assigned depending on the cancer type. NSCLC is assigned a stage (1-4), while SCLC is categorized as limited or extensive.
This article will cover:
Non-small cell lung cancer stages
NSCLC is categorized by the following six stages, depending on when it’s discovered:
Occult-stage NSCLC
Neither imaging nor a bronchoscopy can detect the cancer at this stage. As a result, doctors can’t pinpoint its exact location. However, sputum (mucus from the lungs) or bronchial washings (a sample of cells from inside the airways) may reveal the presence of cancer cells. The cancer likely hasn’t metastasized to other parts of the body.
Stage 0 non-small cell lung cancer
Doctors may detect abnormal cells in the lining of the air passages. These may turn cancerous and affect normal tissue nearby, but they haven’t spread throughout other parts of the body.
The subtypes of stage 0 NSCLC are:
- Adenocarcinoma in situ: When abnormal cells are detected in glandular tissue lining the lungs
- Squamous cell carcinoma in situ: When abnormal cells are detected in the tissues that line the respiratory tract. These cells may turn cancerous and affect other nearby tissues.
Stage 1 non-small cell lung cancer
In stage 1, abnormal cells have turned into cancer.
- Stage 1A: The cancer affects the lung only, with a tumor that measures 3 cm or smaller and hasn’t spread to lymph nodes or other areas.
- Stage 1B:
- In some cases, the lung tumor is larger than 3 cm, but smaller than 4 cm, and hasn’t metastasized to lymph nodes.
- In other cases, the lung cancer tumor measures 4 cm or smaller and meets at least one of the following criteria:
- The cancer has reached the main bronchus (a large airway connecting the trachea to the lung), but not the carina (a ridge at the bottom of the trachea that divides the openings of the left and right main bronchi).
- The cancer has reached the innermost tissue that wraps around the lung.
- Either a portion of or the entire lung has collapsed or has pneumonitis (a condition in which the lung becomes inflamed).
- The cancer has not reached nearby lymph nodes.
Stage 2 non-small cell lung cancer
Stage 2 cases are further classified into two subtypes:
- Stage 2A: The lung tumor is smaller than 5 cm, but larger than 4 cm, and hasn’t metastasized to the lymph nodes. In addition, the cancer meets at least one of the following criteria:
- The cancer has reached the main bronchus, but not the carina.
- The cancer has reached the innermost tissue that wraps around the lung.
- Either a portion of or the entire lung has collapsed or has pneumonitis.
- Stage 2B:
- In some cases, the lung cancer tumor measures 5 cm or smaller and has reached lymph nodes located in the same area of the chest as the original tumor—typically lymph nodes in the lung or close to the bronchus. The cancer also meets at least one of the following criteria:
- The cancer has reached the main bronchus, but not the carina.
- The cancer has reached the innermost tissue that wraps around the lung.
- Either a portion of or the entire lung has collapsed or has pneumonitis.
- In other cases, the cancer hasn’t reached the lymph nodes but meets one of the following criteria:
- The tumor is smaller than 7 cm, but larger than 5 cm.
- At least one additional tumor has formed in the same part of the lung where the original tumor was detected.
- The cancer has reached at least one of the following:
- The wall of the chest
- The inner lining of the chest wall
- The tissue that lines the outside of the sac around the heart
- The nerve controlling the diaphragm, or the muscle in between the chest and the abdomen
Stage 3 non-small cell lung cancer
Cases of stage 3 NSCLC are classified into three subtypes.
- Stage 3A:
- In some cases, the lung cancer tumor measures 5 cm or smaller and has reached lymph nodes in the same area of the chest where the original tumor was detected—typically, the lymph nodes in the trachea, aorta of the heart or where the trachea splits into bronchi. In addition, the cancer meets at least one of the following criteria:
- The cancer has reached the main bronchus, but not the carina.
- The cancer has reached the innermost tissue that wraps around the lung.
- Either a portion of or the entire lung has collapsed or has pneumonitis.
- In other cases, the cancer has reached the lymph nodes in the same area of the chest where the original tumor was found—typically, the lymph nodes near the bronchus or in the lung. In addition, the cancer meets one of the following criteria:
- The tumor is larger than 5 cm but smaller than 7 cm.
- At least one additional tumor has formed in the same part of the lung where the original tumor was found.
- The cancer has reached at least one of the following:
- The wall of the chest
- The inner lining of the chest wall
- The tissue that lines the outside of the sac around the heart
- The nerve controlling the diaphragm
- In other cases, the cancer may have reached the lymph nodes in the same area of the chest as the original tumor—typically, the lymph nodes near the bronchus or within the lung. In addition, the cancer meets one of the following criteria:
- The lung cancer tumor is larger than 7 cm.
- At least one additional tumor has formed in a different lobe, or different part, of the lung than where the original tumor was detected.
- The lung cancer tumor is any size and has reached the trachea, carina or esophagus, among other parts of the body.
- Stage 3B:
- In some cases, the lung cancer tumor is 5 cm or smaller, and the cancer has reached the lymph nodes above the collarbone in the same area of the chest as the original tumor, or lymph nodes on the other side of the chest. The cancer also meets at least one of the following criteria:
- The cancer has reached the main bronchus, but not the carina.
- The cancer has reached the innermost tissue wrapping around the lung.
- Either a portion of or the entire lung has collapsed or has pneumonitis.
- In other cases, the lung tumor is any size and has reached the lymph nodes on the same side of the chest as the original tumor—typically, the lymph nodes near the aorta or the heart, the trachea or where the trachea splits into the bronchi. In addition, the cancer meets one of the following criteria:
- At least one additional tumor has formed in the same or a different lobe of the lung as the original tumor.
- The lung cancer tumor has reached the wall of the chest, the inner lining of the chest wall, the diaphragm or the nerve that controls the diaphragm, among other places.
- Stage 3C:
- The lung cancer tumor is any size and has reached the lymph nodes on the same side or the opposite side of the chest. The cancer also meets at least one of the following criteria:
- At least one additional tumor has formed in the same or a different lobe of the lung.
- The lung cancer tumor has reached the wall of the chest, the inner lining of the chest wall, the diaphragm or the nerve that controls the diaphragm, among other places.
Stage 4 non-small cell lung cancer
Cases of stage 4 NSCLC are classified by two subtypes:
- Stage 4A:
The lung cancer tumor is any size, may have reached the lymph nodes, and meets at least one of the following criteria:
- At least one tumor has formed in the lung opposite to where the original tumor formed.
- The cancer has reached the sac around the heart or the tissues wrapping around the lungs.
- The cancer has spread to fluid surrounding the heart or lungs.
- The cancer has reached an organ far away from the lung, such as the brain, liver or kidney.
- Stage 4B:
The cancer has reached various places in at least one organ far away from the lung.
Small cell lung cancer stages
SCLC is categorized into two stages: limited stage or extensive stage.
Limited-stage small cell lung cancer
If SCLC is in the limited stage, the cancer has only reached one area of the chest. For example, it may be found in one lung or cells may have spread to lymph nodes in the same area of the chest as where the cancer was detected. In limited-stage SCLC cases, radiation is typically needed in one area of the body.
Extensive-stage small cell lung cancer
Extensive stage means the cancer has spread throughout the lung and may have metastasized to the other lung, to lymph nodes in the opposite area of the chest, to fluid surrounding the lung or other locations such as the bones.
Lung cancer survival rate
One way to estimate life expectancy when battling cancer is to consider the five-year relative survival rate for that type of cancer. A five-year relative survival rate indicates the likelihood that a person with a specific type and stage of cancer may live for at least five years after the diagnosis, compared with people who don't have cancer. The rate includes the life expectancy of patients who are still in treatment and those who have finished treatment and have no further evidence of disease.
According to the National Cancer Institute SEER Program, the average five-year relative survival rate for lung and bronchus cancer between 2013 and 2019 was about 25.4 percent.
That survival rate, which changes a bit based on how far the cancer has spread, is classified in four ways for lung and bronchus cancer:
- Localized—The cancer is only found in the part of the body where it started. The five-year survival rate for localized lung and bronchus cancer is about 62.8 percent.
- Regional—The cancer is found in nearby lymph nodes. The five-year survival rate for regional lung and bronchus cancer is about 34.8 percent.
- Distant—The cancer has spread from the lungs or bronchus to other organs, such as the liver. The five-year survival rate for distant lung and bronchus cancer is about 8 percent
- Unknown—When lung or bronchus cancer hasn't been staged, it's considered unknown. The five-year survival rate for unknown lung and bronchus cancer is about 15 percent.
An estimated 53 percent of lung and bronchus cancer cases are diagnosed at the distant stage, after it’s metastasized.
That said, the five-year survival rate has been improving, from around 15 percent in 2000 to 25 percent in 2015. Experts hope these survival rates continue to improve with new therapies and treatment approaches.
Learn about the five-year survival rates for non-small cell lung cancer and for small-cell lung cancer.
