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About staging and grading

Information about staging and grading bone cancer and what this means for your treatment.

This page is about cancer that starts in your bone (primary bone cancer).

If your cancer has spread into bone from another part of the body, it is called secondary or metastatic bone cancer.

Staging bone cancer

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

The tests and scans you have to diagnose your cancer give some information about the stage.

In bone cancer, staging also takes into account how abnormal the cells look under the microscope (the grade).

Your doctors and surgeons might use one of 3 different systems to stage your bone cancer. These are:

  • the Enneking stages
  • the TNM stages
  • the number stages

They will explain which one they are using and what this means for you.

Staging and grading for bone cancer is complicated. The most common system doctors use is the number system.

Grading bone cancer

Doctors grade cancer cells according to how the cells look under a microscope. The grade of the bone cancer gives your specialist a guide to how the cancer may behave.

Low grade cancers have cells that look slightly abnormal. These cancers usually grow slowly and are less likely to spread.

High grade cancers have cells that look very abnormal. These cancers are likely to grow more quickly and are more likely to spread.

In the TNM system, bone cancer cells are graded from GX to G4:

  • GX means the grade cannot be assessed
  • Grades 1 and 2 are low grade tumours
  • Grades 3 and 4 are high grade tumours

All Ewing's sarcomas are high grade (G4).


Doctors sometimes use the term differentiation. This means how developed or mature a cell is:

  • grade 1 cancer cells are well differentiated and look very much like normal cells
  • grade 2 cancer cells are moderately differentiated.
  • grade 3 cancer cells are poorly differentiated and look very abnormal.

If the cancer cells are completely undifferentiated (grade 4), the cells are so abnormal it may not be possible to tell what type of cell they originally came from.

The Enneking stages

The Enneking system is a surgical staging system. Your surgeon uses it to decide how much bone to remove when they operate on the cancer.

The TNM stages

TNM stands for Tumour, Node and Metastasis. The system describes:

  • the size of your primary tumour (T)
  • whether the cancer has spread to your lymph nodes (N)
  • whether the cancer has spread to a different part of your body (metastasised) (M)

The number stages

The tumour, node and metastasis results are put together with the grading to give the number stage.

Stage 0

This is also known as carcinoma in situ. It's a very early, small, low grade cancer that has not spread.

Stage 1A

This is a low grade tumour which is less than 8 cm across.

Stage 1B

This is a low grade tumour more than 8 cm across. Or it is in more than one place in the same bone.

Stage 2A

This is a high grade tumour less than 8 cm across. And with no lymph nodes affected and no metastases.

Stage 2B

This is a high grade tumour more than 8 cm across. There are no lymph nodes affected and no metastases.

Stage 3

There is a high grade tumour in more than one place on the same bone.

Stage 4A

This is any size or grade of tumour that has spread to the lung.

Stage 4B

This means any size or grade of tumour that has spread to the lymph nodes and / or a part of the body other than the lung.

You can call the Cancer Research UK nurses on freephone 0808 800 4040, 9am to 5pm, Monday to Friday. They can help you understand what stage or grade of bone cancer means for your treatment.


As well as the stage and grade of your bone cancer, your treatment will depend on other factors. These include where your cancer is and your general health. Treatment for bone cancer can include:

  • surgery
  • radiotherapy
  • chemotherapy
  • targeted cancer drugs (biological therapy)
Last reviewed: 
21 Nov 2017
  • UK guidelines for the management of bone sarcomas
    C Gerrand and others
    Clinical Sarcoma Research, 2016. Volume 6

  • Cancer and its management (7th edition)
    J Tobias and D Hochhauser
    Blackwell, 2015

  • World Health Organization classification of tumours: pathology and genetics of tumours of soft tissue and bone
    International Agency for Research on Cancer (IARC), 2002

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