TNM staging of bone cancer

The TNM staging system looks at the size of the tumour and whether it has spread to the lymph nodes and different parts of the body. Treatment is often decided according to the stage of the cancer.

The tests and scans you have to diagnose your cancer give some information about the stage. In primary bone cancer, staging also takes into account how abnormal the cells look under the microscope (the grade).

There are different systems for staging primary bone cancer. The most common system used by doctors is the TNM staging system.

Or they might use the number staging system.

The TNM system

TNM stands for Tumour, Node and Metastasis.

The TNM staging system on this page is for bone cancers of the bones in the arms and legs, chest and ribs (trunk), head (skull), and face. Bone cancers of the pelvis and back (spine) use different T stages.

Talk to your doctor about the stages of these cancers.

Tumour (T)

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

T (tumour) is divided into 3 stages - T1 to T3.

T1 means the tumour is 8 cm or less across.

T2 means the tumour is more than 8 cm across.

T3 means there is more than one area of cancer in the same bone.

Node (N)

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

N (node) is divided into 2 stages - N0 and N1.

N0 means there are no cancer cells in lymph nodes close to the tumour.

N1 means there are cancer cells in nearby lymph nodes.

Metastasis (M)

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

M (metastasis) is divided into 3 stages - M0, M1a and M1b.

M0 means the cancer has not spread to any other part of the body.

M1a means the cancer has spread to the lung.

M1b means the cancer has spread to other areas of the body apart from the lung.


The stage of your cancer helps your doctor to decide which treatment you need. Treatment also depends on:

  • your type of cancer (the type of cells the cancer started in)
  • where the cancer is 
  • other health conditions that you have

The stage of the cancer and these other factors can also give an idea of your outlook (prognosis).

Treatment might include:

  • surgery
  • radiotherapy
  • chemotherapy
  • targeted cancer drugs

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