About staging and grading for bone cancer

The different staging systems for bone cancer, as well as the grading, help your doctor to decide on the best treatment for you.

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 2 different systems to stage your bone cancer. These are:

• 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 TNM 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 very much like normal cells. 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 G3:

• grade X (GX) means the grade cannot be assessed
• grade 1 (G1) means the cells look similar to normal bone cells (low grade)
• grade 2 (G2) means the cells look quite different to normal bone cells (high grade)
• grade 3 (G3) means the cells look very different to normal bone cells (high grade)

All Ewing sarcomas are high grade (G3).

Differentiation

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

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

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 1A

The tumour is 8 cm or less across. No lymph nodes are affected and it has not spread to different parts of the body. The tumour is low grade or the grade can't be assessed.

Stage 1B

The tumour is more than 8 cm across, or in more than one place in the same bone. No lymph nodes are affected and it has not spread to different parts of the body. The tumour is low grade or the grade can't be assessed

Stage 2A

The tumour is 8 cm or less across. No lymph nodes are affected and it has not spread to different parts of the body. The tumour is high grade.

Stage 2B

The tumour is more than 8 cm across. No lymph nodes are affected and it has not spread to different parts of the body. The tumour is high grade.

Stage 3

The tumour is in more than one place in the same bone. No lymph nodes are affected and it has not spread to different parts of the body. The tumour is high grade.

Stage 4A

The tumour is any size or grade and has spread to the lung. No lymph nodes are affected.

Stage 4B

The tumour is any size, or more than one place in the same bone. It may or may not have spread to the lymph nodes and different parts of the body. The tumour is any grade.

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