TNM staging is a system that has been used to stage lung cancer since 1966. The system measures the size of tumors, the number of affected lymph nodes, and how far cancer has spread.

As with other types of cancer staging, the TNM system assigns higher numbers to more advanced cancer. Understanding your TNM stage can help you understand the outlook for your lung cancer and treatment options.

Oncologists use a system called staging to assess how far certain types of cancer have progressed. Lower numbered stages indicate that the cancer is contained to one organ or body system, while higher numbered stages mean that cancer has spread to other parts of the body.

Staging systems are used to determine a treatment plan and also serves as a way to quickly convey the severity of a person’s lung cancer.

The most commonly used staging system for lung cancer is called the TNM system. The TNM system measures both tumor size and the spread of cancer.

Oncologists can determine a person‘s TNM stage through the same testing that allows them to diagnose lung cancer. Your initial cancer diagnosis will be staged based on tumor size and the spread of the cancer, but you’ll be restaged throughout your treatment.

The TNM system stands for:

  • Tumor. The “T” measure focuses on the growth of the primary tumor.
  • Node. The “N” focuses on the number of lymph nodes around the lungs where cancer cells are present.
  • Metastasis. The “M” assesses how far the cancer has spread, or metastasized, to other organs and tissues.

The TNM system has been in use since 1966. Over the decades, the system has been updated several times to include more details and more exact staging. It is currently in its 8th edition, with a 9th edition in development.

The system uses letters and numbers to describe the progression of cancer. The letters indicate the part of the body affected, and the numbers indicated the severity. Next we‘ll describe the meaning of each TNM stage in lung cancer.

Stages progress from the occult to stage 4, and each stage is broken down into more exact staging.

In the occult stage, there is no tumor, and cancer cells have not spread to the lymph nodes or throughout the body. Lung cancer is in the occult stage when cancer cells are found in lung fluids, but there is no formed tumor. The occult stage is given these letters and numbers:

  • TX: no tumor
  • NO: no spread to lymph nodes
  • MO: no spread to other parts of the body

If a tumor is present, lung cancer will be staged at 0 or higher. The combination of your tumor, nodule, and metastasis stages will determine your overall stage. This chart offers a breakdown of each stage.

Lung cancer stageTNM stage
stage 0TIS, NO, MO
stage 1A1T1mi, T1a, NO, MO
stage 1A2T1b, NO, MO
stage 1A3T1c, NO, MO
stage 1BT2A, NO, MO
stage 2AT2B, NO, MO
stage 2BT1a through T2b, N1, MO
stage 3AT1a through T4, NO though N1, MO
stage 3BT1a through T4, N2 though N3, MO
stage 3CT3 through T4, N3, M0
stage 4aAny T, Any N, M1a or M1B
stage 4BAny T, Any N, M1C

Tumor stages 0 to 4

TNM stage 0 refers to a tumor found in the top layers of cells in your air passages. It has not spread to your lymph nodes or other bodily systems. The tumor stage is written as TIS. Additional tumor stages include:

  • T1mi. At stage T1mi, the portion of the tumor that has spread into your lung tissue is 0.5 centimeters (cm) or smaller.
  • T1a. At stage TIa, the tumor is 1 cm or smaller and has not spread to your bronchi or the membranes around your lungs.
  • T1b. At stage T1b, the tumor is between 1 and 2 cm and hasn’t spread to your bronchi or the membranes around your lungs.
  • T1c. At stage T1c, the tumor is between 2 and 3 cm and hasn’t spread to your bronchi or the membranes around your lungs.
  • T2a. At stage T2a, the tumor is between 3 and 4 cm and has spread to your bronchi or the membranes around your lungs, or is partially blocking your airway.
  • T2b. At stage T2b, the tumor is between 4 and 5 cm and has spread to your bronchi or to the membranes around your lungs, or is partially blocking an airway.
  • T3. At stage T3, the tumor is either between 5 and 7 cm, has spread to the chest wall, parietal pleura, phrenic nerve, or parietal pericardium, or has at least two nodules in a lobe of the lung.
  • T4. At stage T4, the tumor meets at least one of the following criteria:
    • greater than 7 cm
    • has spread to the spine, carina, trachea, esophagus, diaphragm, or heart
    • there are at least two nodules in different lobes of the same lung

Nodule stages 0 to 3

Nodule, or spread to the lymph node, also has stages. Higher stages indicate a greater severity and further spread:

  • N0. At stage N0, there is no spread to the lymph nodes.
  • N1. At stage N1, cancer is present in the lymph nodes on the same side as the primary tumor.
  • N2. At stage N2, the cancer is present in the lymph nodes between the lungs and on the same side as the primary tumor.
  • N3. At stage N3, the cancer is present in the lymph nodes near the collarbone on both sides, and might be present in the lymph nodes on the opposite side of the lungs from the primary tumor.

Metastasis stages 0 or 1

The staging for metastasis is based on how far cancer has spread to other regions of your body. For lung cancer, these include:

  • M0. At stage M0, there is no spread to other body parts.
  • M1a. At stage M1a, cancer has spread to either both lungs, the fluid in the pericardium (sack) around the heart, or any tissue around the lungs.
  • M1b. At stage M1b, cancer has spread to an organ such as the brain or a lymph node beyond the chest cavity.
  • M1c. At stage M1c, the cancer is present in multiple lymph nodes or organs outside the chest cavity.

Any cancer diagnosis can be overwhelming. It’s important to take care of yourself and find support while your cancer is being treated.

The right support for you will depend on your situation and personal preferences. For example, if you’re religious, church-based groups might be helpful. If you have family close, they might be able to offer support and assistance.

Other options for support include:

  • reaching out to friends to talk or for help with a task
  • talking with your oncologist about each step of your treatment to ensure you understand it
  • asking your oncologist about social workers or therapists who have worked with lung cancer patients
  • finding local support groups to connect with other lung cancer patients
  • joining online support groups or forums

There are several resources that can help you find a support group, including:

The TNM staging system is used by oncologists to pinpoint how far along lung cancer has progressed. It measures tumor growth, spread to lymph nodes, and overall spread. Lower stages of lung cancer have not spread, while higher stages indicate advanced cancer.

The TNM stage can help your doctor determine the best treatment options for you, and help you understand the progression of your lung cancer.