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Enneking staging system

The Enneking system helps your surgeon decide about treatment for cancer that starts in your bone (primary bone cancer).

The stage of a cancer tells the doctor how big it is and whether it has spread. Treatment is often decided according to the stage of the cancer. 

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

There are different systems for staging bone cancer. Your doctors might use the Enneking staging system or another staging system called TNM.

Enneking stages

The Enneking system is based on the:

  • grade (G) - how the cells look under a microscope
  • site of the cancer in the bone (T)
  • metastases (M) - whether the cancer has spread to another part of the body
In the Enneking system bone cancer tumours are graded from G0 to G2.
  • G0 means a non cancerous (benign) tumour
  • G1 means low grade cancer
  • G2 means high grade cancer

The Enneking system divides bone cancers into 3 stages:

  • Stage 1 means the cancer is low grade
  • Stage 2 means the cancer is high grade
  • Stage 3 means that the cancer has spread to another part of the body (metastasised)

Stages 1 and 2 are divided into A and B:

  • A means the cancer is still within the bone
  • B means the cancer has grown through the bone wall

Stage 1A 

This is a low grade bone cancer that is still completely inside the bone in which it started. The tumour may press on the bone wall and cause swelling. But the cancer has not grown through the bone wall or spread to any other part of the body. This is called an intracompartmental bone cancer.

Diagram showing stage 1A bone cancer

Stage 1B 

This bone cancer is low grade but has grown through the bone wall. It is called an extracompartmental bone cancer. This means the cancer has grown out of the area (compartment) of the bone in which it started.

Diagram showing stage 1B bone cancer

Stage 2A 

This cancer is high grade but still completely within the bone in which it started. It has not spread to other areas of bone or any other part of the body. It is an intracompartmental cancer.

Diagram showing stage 2A bone cancer

Stage 2B 

This cancer is high grade and has grown through the wall of the bone into nearby tissues. It's an extracompartmental cancer. This means it's grown out of the area (compartment) of bone in which they started.

Diagram showing stage 2B bone cancer

Stage 3

The cancer has spread to other bones or another area of the body. The most common site for bone cancer to spread to is the lungs. The second most common area for it to spread to is other bones.

Diagram showing stage 3 bone cancer


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
  • 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

  • UK guidelines for the management of bone sarcomas
    C Gerrand and others
    Clinical Sarcoma Research, 2016

Information and help