What You Need to Know About Lung Cancer Staging

Medically Reviewed By Adithya Cattamanchi, M.D.
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Lung cancer staging determines the size of the main tumor, whether lymph nodes are affected, and whether and how far the cancer has spread. Doctors use two staging systems for non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), the two main types of lung cancer.

Read on to learn about lung cancer staging and the tests doctors may use.

What is lung cancer staging?

A conceptual picture of the lungs set against a pink background
Beatrix Boros/Stocksy United

The lung cancer staging process determines how much cancer is in the body. Doctors look at a few factors in evaluating cancer stages:

  • the size of the primary tumor
  • whether any lymph nodes are affected
  • if and where the cancer has spread farther into the body

These factors help doctors decide on the best treatment for a person’s situation.

How do doctors classify the stages of non-small cell lung cancer?

To stage NSCLC, doctors use the Tumor, Nodes, and Metastasis (TNM) system:

  • Tumor (T): How large is the tumor, and has it spread to nearby structures?
  • Nodes (N): Are nearby lymph nodes affected?
  • Metastasis (M): Has cancer spread to distant parts of the body?

This system lays out stages 0 through 4. Generally, the lower the stage number, the less cancer has spread into the body.

Lung cancer staging can be complex. Your doctor can help you understand the stages and what they mean for your situation.

Below is a simplified layout of the lung cancer stages.

  • Stage 0: The cancer is present only in the top layer of cells in the air passage lining. It has not spread to adjacent lymph nodes or distant body sites.
  • Stage 1: This stage can be subdivided into stages 1A or 1B.
    • In stage 1A, the primary tumor is no larger than 3 centimeters (cm) across. It may or may not have spread deeper into the lung tissues but has not affected nearby lymph nodes or distant body sites.
    • In stage 1B, the primary tumor is 3–4 cm across. It may have spread into nearby structures or membranes and partially blocked the airways. It has not spread to nearby lymph nodes or distant body sites.
  • Stage 2: This stage can be subdivided into stages 2A or 2B.
    • In stage 2A, the primary tumor is 4–5 cm across. It has spread into nearby structures or membranes and may partially block the airways. It has not spread into nearby lymph nodes or distant body sites.
    • In stage 2B, the primary tumor may be 3–7 cm across. It may affect lymph nodes on the same side of the lung or nearby structures. It may partially block the airways, and there may be more than one tumor nodule in the same lung lobe.
  • Stage 3: This stage can be subdivided into 3A, 3B, or 3C.
    • In stage 3A, the primary tumor may be 3–7 cm or more across. It may have spread farther into the chest, and there may be 2 or more tumor nodules in the same lung lobe. It has not spread to distant body sites.
    • In stage 3B, the primary tumor may be more than 7 cm across. Lymph nodes on either side of the body and additional structures in the chest space may be affected. Distant body sites are not affected yet.
    • In stage 3C, the primary tumor can be across 5–7 cm or more. It may affect additional structures in the chest, and there may be 2 or more tumor nodules in the same lung lobe.
  • Stage 4: This stage can be subdivided into 4A or 4B.
    • In stage 4A, the primary tumor can be any size and may have spread into the other lung or additional structures in the chest. It may also have spread outside the chest into distant body sites.
    • In stage 4B, the primary tumor can be any size and has spread into distant body sites.

Learn more about non-small cell lung cancer.

How do doctors classify the stages of small cell lung cancer?

The stages of SCLC are less complex than NSCLC. Doctors generally describe SCLC as either “limited stage” or “extensive stage.”

Limited stage SCLC

Limited stage means lung cancer is present only in one side of the chest and may be treatable with one radiation field. Only about one-third of people with SCLC are diagnosed at the limited stage.

Extensive stage SCLC

Extensive stage means that lung cancer has grown:

  • throughout the lung or to the other lung
  • to lymph nodes on the other side of the chest
  • to other body sites

Learn more about small cell lung cancer.

What tests do doctors use in the lung cancer staging process?

Doctors can use several tests in the lung cancer staging process. If they suspect lung cancer, they might initially use imaging tests to look for areas of concern. These tests include:

  • chest X-rays
  • CT scans
  • MRI scans
  • PET scans
  • bone scans
  • ultrasounds

These imaging tests can also help determine the extent of cancer spread.

Once doctors have narrowed down a suspicious area, they can use additional tests to confirm a diagnosis:

  • sputum cytology, which involves examining a lung sputum sample for cancerous cells
  • thoracentesis, which involves removing fluid from around the lungs to look for cancerous cells
  • biopsy, which removes a small sample of tissue from the lung to look for cancerous cells

Learn more about lung cancer diagnosis.

Other frequently asked questions

Learn the answers to a few other common questions about lung cancer and staging. Adithya Cattamanchi, M.D., has reviewed the answers.

How does your lung cancer stage affect life expectancy?

A higher stage of lung cancer is associated with poorer outcomes. According to researchers, most people receive a lung cancer diagnosis in the later stages of the disease. This can make treatment much more difficult.

How long can you live with lung cancer?

Life expectancy with lung cancer depends on a few factors, such as the stage of the disease at the time of diagnosis and the individual’s overall health. According to the American Cancer Society, the 5-year relative survival rates for lung cancer drop significantly as the disease progresses.

A relative survival rate shows how long someone with a specific condition may live after their diagnosis compared with someone without the condition. 

For example, a 5-year relative survival rate of 70% means that 70 out of 100 people diagnosed with a condition are still living at least 5 years from the time of diagnosis.

It’s most important to remember that figures are estimates, and everyone is different. Talk with your doctor about your specific condition.

Summary

The lung cancer staging process for NSCLC and SCLC can be complex. Your doctor can help you understand the specifics of each stage and how your treatment plan may change.

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Medical Reviewer: Adithya Cattamanchi, M.D.
Last Review Date: 2022 Nov 7
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