How do the number and TNM lung cancer stages fit together?

This page tells you about how the two staging systems for lung cancer fit together. There is information about

 
 

What cancer staging is

Staging for cancer includes information about the size of the tumour, whether there is cancer in the lymph nodes and whether it has spread anywhere else in the body. It is important because it helps your doctor decide about which treatment you need. The tests and scans you have to diagnose your cancer give some information about the stage.

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The TNM and number staging systems

There are two ways of staging lung cancer – the number and TNM staging systems. You are most likely to be told the number stage of your cancer.

The number system divides the stages into 4 main stages, from 1 to 4. Stage 1 is a small cancer just affecting the lung. Stages 2 and 3 mean the cancer has spread into lymph nodes or other organs close to the lung. And stage 4 is when the cancer has spread to another organ in the body.

The TNM staging system takes into account the size of the tumour (T), whether cancer cells have spread into the lymph nodes (N) close to the cancer and whether the tumour has spread anywhere else in the body, which is called a secondary cancer or metastases (M). The doctor gives each of these factors a number.

There is more detailed information about both of these staging systems on the page called more about lung cancer staging in the lung cancer section.

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How the systems fit together for lung cancer

The two staging systems tell your doctor the same thing in a slightly different way. The information below shows how the TNM staging information fits into the number staging system.

Stage 1 lung cancer is divided into two groups, 1A and 1B

  • The TNM stage for 1A lung cancer is T1a or T1b, N0, M0
  • The TNM stage for 1B lung cancer is T2a, N0, M0

Stage 2 lung cancer is divided into two groups, 2A and 2B.

The TNM stage for 2A lung cancer could be any of the below

  • T1a, N1, M0
  • T1b, N1, M0
  • T2a, N1, M0
  • T2b, N0, M0

The TNM stages for 2B lung cancer are either T2b, N1, M0 or T3, N0, M0.

Stage 3 lung cancer TNM stages are a bit more complicated. Again, there are two groups, 3A and 3B. If you have stage 3A lung cancer, you could have any of these TNM stages

  • T1a, N2, M0
  • T1b, N2, M0
  • T2a, N2, M0
  • T2b, N2, M0
  • T3, N1, M0
  • T3, N2, M0
  • T4, N0, M0
  • T4, N1, M0

If you have stage 3B lung cancer, you have any of the following

  • Any T, N3, M0
  • T4, N2, M0
  • T4, N3, M0

Stage 4 lung cancer is TNM stage – Any T, any N, with M1A or M1B.

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