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Lung Cancer TNM Staging


Updated May 16, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

TNM staging for lung cancer can be confusing for anyone to understand, let alone someone who has just been hit with the news of diagnosis. What do those letters and numbers mean? How does TNM staging help my doctor recommend the best treatment for my lung cancer? How does TNM staging align with the lung cancer stages, like stage 2 and stage 4?

What Do the Letters Mean?

  • T – Stands for the size of the tumor. Tumor size is usually given in centimeters (cm). To understand this in inches, 5 cm is about the same as 2 inches.

  • N – N stands for lymph nodes and tells whether the tumor has spread to lymph nodes, and if so, how far away from the tumor they are.

  • M – M stands for metastasis, that is, the spread of the tumor to other parts of the body.

Why Is it Important?

TNM staging helps doctors understand how extensive a cancer is and, therefore, what the best treatment options are for that particular cancer. It can also help predict what the average prognosis is for someone with lung cancer. TNM staging is based on worldwide data on lung cancer in thousands of people and comparisons of the extent of lung cancer with responses to treatment and prognosis.

That said, it is very important to understand that there are many factors that affect the prognosis of a lung cancer that go beyond the stage. Your general health, the particular type of lung cancer you have, and even your gender can play a role in what treatments will work best for you and what your individual prognosis is.

Lung Cancer TNM Staging Breakdown

T - Tumor Size

  • Tx – The tumor size is unknown, or cancer cells are only found in sputum.

  • T0 – There is no evidence of a primary tumor.

  • TisCarcinoma in situ – The tumor is present only in the cells lining the airway and has not spread to nearby tissues.

  • T1 – Tumors less than or equal to 3 cm (1 ½ inches).
    • T1a – Less than or equal to 2 cm.
    • T1b – Greater than 2 cm but less than or equal to 3 cm.
  • T2 – The tumor is greater than 3 cm but less than 7 cm. T2 tumors may block part of the airway, but have not resulted in pneumonia or caused the lung to collapse (atelectasis). They may have spread to the lining around the lungs. They may also be close to the main bronchus, but are at least 2 cm (about an inch) away from the area in which the bronchus divides to go to each of the lungs.
    • T2a – Greater than 3 cm but less than or equal to 5 cm.
    • T2b – Greater than 5 cm but less than or equal to 7 cm.
  • T3 – Tumors greater than 7 cm, or less than 7 cm but with a separate nodule in the same lobe. T3 tumors also include tumors that are less than 7 cm but invade the lining of the lung (pleura), the chest wall, the diaphragm, the main bronchus, or lie within 2 cm of the area where the bronchus divides to travel to the lungs. A tumor is also classified as T3 if it is less than 7 cm but is associated with pneumonia or collapse of the entire lung.

  • T4 – A tumor of any size, but with another nodule in a different lobe on the same side of the body, or a tumor that invades structures in the chest such as the heart, major blood vessels near the heart, the trachea, the recurrent laryngeal nerve (a nerve near the trachea), the mediastinum (the space between the lungs), the esophagus, or the area where the main bronchus divides to travel to the two lungs.

N – Involvement of Lymph Nodes

  • N0 – No nodes are involved.

  • N1 – The tumor has spread to nearby nodes on the same side of the body.

  • N2 – The tumor has spread to nodes farther away, but on the same side of the chest.

  • N3 – The tumor has spread to lymph nodes on the other side of the chest from the original tumor, or has spread to nodes near the collarbone or neck muscles.

M – Metastasis (Spread) to Other Regions

  • M0 - The tumor has not spread to distant regions.

  • M1
    • M1a – The tumor has spread to the opposite lung, to the lung lining (malignant pleural effusion) or has formed nodules on the pleura.

    • M1b – The tumor has spread to distant regions of the body, such as the brain or bones.

Comparison of Lung Cancer Stages and TNM Staging

Most people are more familiar with the stages of lung cancer than they are with TNM staging. Here is a comparison of lung cancer stages and TNM staging:

Stage 0 Lung Cancer

  • TisN0M0

Stage 1 Lung Cancer

  • Stage 1A Lung Cancer
    • T1aN0M0
    • T1bN0M0
  • Stage 1B Lung Cancer
    • T2aN0M0

Stage 2 Lung Cancer

  • Stage 2A Lung Cancer
    • T1aN1M0
    • T1bN0M0
    • T2aN1M0
  • Stage 2B Lung Cancer
    • T2bN0M0
    • T2bN1M0
    • T3N0M0

Stage 3 Lung Cancer

Stage 4 Lung Cancer

  • Any T, Any N, M1a
  • Any T, Any N, M1b


Edge, S. et al (Eds.). AJCC Cancer Staging Manual. 7th Edition. Springer. New York, NY. 2010.

National Cancer Institute. Non-Small Cell Lung Cancer Treatment (PDQ). Stage Information for Non-Small Cell Lung Cancer. Updated 08/15/12. http://www.cancer.gov/cancertopics/pdq/treatment/non-small-cell-lung/HealthProfessional/page3

Rami-Porta, R., Crowley, J., and PP. Goldstraw. The Revised TNM Staging System for Lung Cancer. Annals of Thoracic and Cardiovascular Surgery. 2009. Vol 12, No 1.

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