TNM staging

TNM staging

Get information about the tumour, node and metastasis (TNM) staging system for lung cancer.

The stage of a cancer tells you how big it is and whether it has spread. Knowing the stage helps your doctor decide which treatment you need.

Your scans and tests will give some information about the stage of your cancer. But your doctor might not be able to tell you the exact stage until after you have surgery.

The TNM staging system is the most common way for doctors to stage non small cell lung cancer. And it is sometimes used for small cell lung cancer.

TNM stands for Tumour, Node, Metastasis.

Doctors use the TNM system to create a number staging system: with stages 1 to 4.

Doctors sometimes use a simpler staging system for small cell lung cancer. They might describe it as limited disease or extensive disease.

Tumour (T)

Tumour describes the size of the tumour (area of cancer). This is a simplified description of the T stage.

There are 4 categories – T1 to T4.

TX means the main cancer (primary) can’t be assessed. It doesn’t show on scans but there might be cancer cells present in spit or in fluid taken from the lung.

T0 means there is no sign of cancer.

Tis means an area of cancer cells contained within the inner lining of the lungs.


T1 means the cancer is contained within the lung.

It is divided into T1a, T1b, and T1c according to the diameter of the cancer.

T1a means the cancer is 1cm or less at its widest part.

T1b means the cancer is between 1cm and 2cm across.

T1c means the cancer is between 2 and 3 cm across.


T2 can mean different things.

The cancer is between 3cm and 5cm across.

Or the cancer has one or more of the following features:

  • It involves the main airway (the main bronchus) but is not close to the area where the bronchus divides to go into each lung.
  • It involves the inner lining of the chest cavity (the visceral pleura).
  • Part or all of the lung has collapsed or is blocked due to inflammation.

T2 is divided into T2a and T2b.

T2a means the cancer is between 3cm and 4cm.

T2b means the cancer is between 4cm and 5cm.


T3 can mean different things.

The cancer is between 5cm to 7cm.

Or there is more than one tumour in the same lobe of the lung.

Or the cancer has grown into one or more of these structures:

  • The chest wall (the structures around the lungs, such as ribs, muscles, cartilage, or the diaphragm).
  • The nerve close to the lung (phrenic nerve).
  • The outer covering of the heart (the pericardium).


T4 can mean different things.

The cancer is bigger than 7cm.

Or it is in more than one lobe of the lung.

Or it has spread into one or more of the following structures:

  • the muscle under the lungs (the diaphragm).
  • the area between the lungs in the middle of the chest (the mediastinum).
  • the heart.
  • a major blood vessel.
  • the wind pipe (trachea).
  • the nerve that controls the voice box.
  • the food pipe (oesophagus).
  • a spinal bone.
  • the area where the main airway divides to go to each lung.

Node (N)

Node (N) describes whether the cancer has spread to the lymph nodes.

NX means that the lymph nodes can’t be assessed.

N0 means that the lymph nodes don’t contain cancer cells.


N1 means there are cancer cells in lymph nodes within the lung or in lymph nodes in the area where the lungs join the airway (the hilum).


N2 means there is cancer in lymph nodes:

  • in the centre of the chest (mediastinum) on the same side as the affected lung or
  • just under where the windpipe branches off to each lung


N3 means there is cancer in lymph nodes:

  • on the opposite side of the chest from the affected lung or
  • above the collar bone or
  • at the top of the lung

Metastasis (M)

Metastasis (M) describes whether the cancer has spread to a different part of the body.

M0 and M1

There are 2 stages of metastasis – M0 and M1.

M0 means the cancer hasn’t spread to another lobe of the lung or any other part of the body

M1 means the cancer has spread to other areas of the body. It is split into M1a, M1b and M1c.

M1a means one or more of the following:

  • there is cancer in both lungs
  • there are areas of cancer around the heart or in the lining around the lung
  • there is fluid around the lung or heart that contains cancer cells – this is called a malignant pleural effusion or a pericardial effusion

M1b means that there is a single area of cancer outside the chest in an organ (such as the liver or brain) or a lymph node.

M1c means that there is more than one area of cancer in one or several organs.


Back to Stages, Types and Grades.