Staging

The stage of a cancer is a term used to describe its size and whether it has spread. Knowing the stage of your cancer helps doctors decide on the best treatment for you.

The stages of melanoma are:

  • Melanoma in situ (stage 0): This is a term used to describe the earliest stage of melanoma. This means the melanoma cells are only in the top layer of skin (epidermis) and have not started to spread into the lower layer of the skin (the dermis).
  • Stages 1 and 2: The melanoma is only in the skin and has not spread anywhere else in the body.
  • Stage 3: The melanoma has spread to the nearest lymph vessels or nodes, but not to anywhere else in the body.
  • Stage 4: The melanoma has spread to distant areas of skin, or to other organs such as the lung, liver or brain. This is called advanced or metastatic melanoma.

When melanomas are staged, doctors also use a measurement to describe how thick (deep) the melanoma is. This is called the Breslow thickness.

Staging melanoma

The stage of a cancer is a term used to describe its size and whether it has spread. Knowing the stage of your cancer helps doctors decide on the best treatment for you.

Your specialists can give you more information about the stage of your melanoma.

Melanoma in situ (stage 0)

Melanoma in situ is a term used to describe the earliest stage of melanoma. It is also called melanocytic intraepithelial neoplasia. This means the melanoma cells are only in the top layer of skin (epidermis) and have not started to spread into the lower layer of the skin (the dermis). Because of this, people with melanoma in situ do not usually have any risk of the melanoma spreading to other parts of the body.

Stages 1 and 2

The melanoma is only in the skin and has not spread anywhere else in the body.

Stage 3

The melanoma has spread to the nearest lymph vessels or nodes, but not to anywhere else in the body.

Stage 4

The melanoma has spread to distant areas of skin, or to other organs such as the lung, liver or brain. This is called advanced or metastatic melanoma.


Breslow thickness

When melanomas are staged, doctors also use a measurement to describe how thick (deep) the melanoma is. This is called the Breslow thickness. It measures in millimetres (mm) how far the melanoma cells have grown down into the layers of skin.

Most people have melanomas that are 1mm thick or less. These are stage 1 melanomas. They are often known as thin melanomas and they are very unlikely to spread. Most can be cured by a simple operation called a wide local excision.

If a melanoma is thick, it is more likely to spread into the lymph vessels or nodes closest to the melanoma. If this happens, additional surgery will be needed to remove the lymph nodes as well as the melanoma.

The different levels of tumour thickness

Stages of melanoma - with Tis
Stages of melanoma - with Tis

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There are five levels of tumour thickness:

  • Tis – the melanoma cells are only in the very top layer of the skin (epidermis).
  • T1 – the melanoma is 1mm thick or less.
  • T2 – the melanoma is between 1mm and 2mm thick.
  • T3 – the melanoma is between 2mm and 4mm thick.
  • T4 – the melanoma is more than 4mm thick.


Detailed staging of melanoma

A detailed staging system used for melanoma is the American Joint Committee on Cancer (AJCC) system. It uses the TNM system:

  • T stands for tumour. It describes the thickness (depth) of the melanoma and uses the Breslow thickness. It also describes whether the melanoma is ulcerated and what its mitotic rate is. A melanoma is ulcerated if the layer of skin covering the melanoma is broken. Mitotic rate describes the number of cells that are in the process of dividing in a certain amount of melanoma tissue. A higher mitotic rate means that the cancer has a greater risk of spreading.
  • N stands for lymph nodes. It describes whether the melanoma has spread to the lymph nodes and, if so, to how many.
  • M stands for metastases. It describes whether the melanoma has spread to other parts of the body (secondary or metastatic cancer).

The AJCC system groups melanomas into an overall number stage between 0 and 4.

Stage 0 – the melanoma is only in the top layer of the skin (epidermis). It has not begun to spread into deeper layers.
Stage 1 melanoma is no more than 2mm thick and has not spread beyond the skin. Stage 1 is divided into two sub-stages.
Stage 1AThe melanoma is 1mm thick or less, without ulceration. It has a mitotic rate of less than 1/mm2.
Stage 1BThe melanoma is 1mm thick or less. It also has either ulceration or a mitotic rate of at least 1/mm2.
or
The melanoma is between 1.01mm and 2mm thick, but doesn’t have ulceration.
Stage 2 – the melanoma has not spread to the lymph nodes or anywhere else in the body. Stage 2 is divided into three sub-stages.
Stage 2AThe melanoma is between 1.01mm and 2mm thick, with ulceration.
or
The melanoma is between 2.01mm and 4mm thick, without ulceration.
Stage 2BThe melanoma is between 2.01mm and 4mm thick, with ulceration.
or
The melanoma is thicker than 4mm, without ulceration.
Stage 2CThe melanoma is thicker than 4mm with ulceration.
Stage 3 – the melanoma has spread to the lymphatic vessels or lymph nodes closest to the melanoma. It has not spread to anywhere else in the body. It can be of any thickness. Stage 3 is divided into three sub-stages.
Stage 3AThe melanoma has spread into up to three lymph nodes. The melanoma cells in the nodes can only be seen under a microscope (micrometastasis). There is no ulceration.
Stage 3BThe melanoma is ulcerated and has spread into up to three lymph nodes. The melanoma cells in the nodes can only be seen under a microscope.
or
The melanoma has spread into up to three lymph nodes. The nodes are enlarged (macrometastasis). There is no ulceration.
or
The melanoma has spread into two or three lymph nodes. It has also spread to the skin or lymphatic vessels near the melanoma. There is no ulceration.
Stage 3CThe melanoma is ulcerated and has spread into up to three lymph nodes. The nodes are enlarged.
or
The melanoma is ulcerated. It has spread into two or three lymph nodes. It has also spread to the skin or lymphatic vessels near the melanoma.
or
The melanoma may or may not be ulcerated. It has spread into four or more lymph nodes.
or
The melanoma may or may not be ulcerated. It has spread into lymph nodes that have joined together.
Stage 4 – the melanoma has spread to distant areas of skin or distant lymph nodes. Or it has spread to other organs such as the lungs, liver or brain.

The way cancers are staged is complicated. If you have any questions about the stage of the melanoma, ask your doctor.

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