Staging and grading of melanoma
The stage of a cancer is a term used to describe the size of the cancer and whether it has spread.
Knowing the stage of your cancer helps doctors decide on the best treatment for you. The staging system used for melanoma is the American Joint Committee on Cancer (AJCC) system. This uses the TNM system.
T stands for tumour. This is based on the thickness (depth) of the melanoma using Breslow thickness. It also looks at whether the melanoma is ulcerated. A melanoma is said to be ulcerated if the layer of skin covering the melanoma can not be clearly seen.
N refers to whether the melanoma has spread to the lymph nodes (sometimes called glands).
M is whether the melanoma has spread to other parts of the body (secondary or metastatic cancer).
The AJCC system combines information from the TNM system to group melanomas into an overall number stage (stage 1-4).
All stage 1 melanomas are no more than 2mm thick and have not spread beyond the skin.
Stage 1 melanoma can be divided into:
The melanoma is 1mm thick or less without ulceration.
The melanoma is 1mm thick or less with ulceration OR between 1.01mm and 2mm thick without ulceration.
Melanomas at this stage have not spread to the lymph nodes or anywhere else in the body.
Stage 2 melanoma can be divided into:
The melanoma is between 1.01mm and 2mm in thickness with ulceration OR between 2.01mm and 4mm without ulceration.
The melanoma is between 2.01mm and 4mm in thickness with ulceration OR thicker than 4mm without ulceration.
The melanoma is thicker than 4mm with ulceration.
Melanomas at this stage have spread to the lymph nodes or lymphatic tubes closest to the melanoma but not to anywhere else in the body. In stage 3 the thickness of the melanoma is not a factor, but the melanoma is usually thick.
Stage 3 melanoma is divided into stages 3A, 3B or 3C, depending on factors such as:
the number of lymph nodes involved
whether the lymph nodes contain melanoma cells that can be seen by the naked eye or only under a microscope
whether melanoma cells are found in the skin or lymphatic tubes near the melanoma.
The melanoma has spread to distant areas of skin or distant lymph nodes, or to other organs such as the lung, liver or brain. This is called advanced or metastatic melanoma.
The most important measurement for melanoma is how thick (deep) it is. This is called the Breslow thickness (named after the doctor who introduced it). It’s the distance in millimetres from the surface of the skin to the deepest melanoma cells.
Most people have melanomas that are 1mm thick or less - these are stage 1 melanomas. These are very unlikely to spread into the lymph nodes and most can be cured by a simple operation known as a wide local excision.
Thick melanomas are more likely to spread into the lymph nodes closest to the melanoma. If the melanoma has spread to the lymph nodes, additional surgery will be needed to remove the lymph nodes as well as the melanoma.
Melanoma in situ (also known as melanocytic intraepithelial neoplasia, MIN) is a term used to describe the very earliest stage of melanoma. The melanoma cells are just in the very top layer of skin (epidermis) and haven’t started to spread down into the dermis. Because the melanoma is only in the very top layer of skin, people with melanoma in situ do not usually have any risk of the melanoma spreading to other parts of the body