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The stages of skin cancer

Men and woman discussing skin cancer

This page tells you about the stages of skin cancer and how they are worked out. You can find the following information

 

A quick guide to what's on this page

Stages of skin cancer

The stage of a cancer tells the doctor how far it has spread. This is important because treatment is often decided according to the stage of a cancer. Most basal cell skin cancers do not need staging because it is very rare for them to spread. Staging is more likely for squamous cell skin cancers because they can spread, although this is still rare.

The TNM staging system

Doctors use a staging system that is common to all cancers. It is called the TNM system. The T indicates the size and depth of the tumour. The N shows whether the cancer has spread to the lymph nodes. The M (metastasis) shows whether the cancer has spread to another part of the body.

The number system

Once the TNM categories (types) have all been decided, the information is put together to give a number stage from 0 to 4. The lower the stage, the earlier the cancer has been diagnosed. 

Stage 0 is also called Bowen’s disease. The cells have started to become cancerous but it is very early. Your doctor may describe this as pre cancerous or pre malignant. If it is not treated, Bowen's disease can develop into a squamous cell skin cancer (SCC). Most SCC's are diagnosed at an early stage (stage 1 or 2).
 

CR PDF Icon You can view and print the quick guides for all the pages in the treating skin cancer section.

 

 

What staging is

The stage of a cancer tells the doctor how far it has spread. This is important because treatment is often decided according to the stage of a cancer.

Your doctor may carry out a number of tests to stage your cancer. But most basal cell cancers do not need staging because it is very rare for them to spread. They will only be staged if they are very large. Staging is more likely for squamous cell skin cancers because they can spread, although this is still rare.

 

The TNM staging system

Doctors use a staging system that is common to all cancers. It is called the TNM system

  • The T indicates the size and depth of the tumour
  • The N shows whether the cancer has spread to the lymph nodes
  • The M shows whether the cancer has spread to another part of the body (metastasis)

There is more about staging in the about cancer section.

 

The number system

Once the TNM categories (types) have all been decided, the information is put together to give a number stage from 0 to 4. The lower the stage, the earlier the cancer has been diagnosed. Most squamous cell skin cancers are diagnosed at stage 1 or 2.

Stage 0

Stage 0 is also called Bowen's disease or carcinoma in situ. Carcinoma means there are cancer cells there. In situ means the cells are still in the place where they started to develop. So the cells have started to turn into cancer, but they have not yet spread or grown into surrounding areas of the skin. If it is not treated, Bowen's disease can develop into a squamous cell skin cancer. So your doctor may describe this stage as pre cancerous or pre malignant.

Stage 1

Stage 1 means the cancer is 2cm across or less and has 1 or no high risk features.

High risk features mean the cancer

  • Is more than 2mm thick
  • Has grown into the lower dermis
  • Has grown into the space around a nerve (perineural invasion)
  • Started on the ear or lip
  • Looks very abnormal under the microscope (the cells are poorly differentiated or undifferentiated)

Stage 2

Stage 2 means the cancer is more than 2cm across, or has 2 or more high risk features.

Stage 3

Stage 3 means the cancer

  • Has grown into the bones in the face, such as the jaw bone or the bone around the eye, OR
  • Has spread to a nearby lymph node (or lymph gland) on the same side of the body (and is less than 3cm)

Stage 4

Stage 4 means the cancer 

  • Has grown into the spine, ribs or lower part of the skull, OR
  • Has spread to a lymph node that is more than 3cm OR to an internal organ, such as the lungs

Staging can be quite complicated, so do talk to your doctor or clinical nurse specialist about what your stage of cancer is and what it means.

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Updated: 4 March 2013