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 a cancer helps doctors decide on the best treatment for you. The staging system that is used for melanoma is the American Joint Committee on Cancer (AJCC).

AJCC staging system

This uses the TNM system.

• T stands for tumour. This is based on the thickness of the melanoma (using Breslow thickness) and also looks at whether the melanoma is ulcerated.
• N stands for spread to lymph nodes (sometimes called glands).
• M is whether the melanoma has spread to other parts of the body (secondary or metastatic cancer).

Breslow thickness

As well as the AJCC system, an important measurement for melanoma is how thick 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 how far down the deepest melanoma cells are. Thin melanomas (less than 1mm) have a very high chance of being cured.

Ulceration

A melanoma is said to be ulcerated if the layer of skin covering the melanoma cannot be clearly seen. If it’s not ulcerated the letter a is added to the stage and if it is ulcerated the letter b is added.

Thin melanoma, less that 1mm, is always stage 1 in the AJCC system. It will either be stage 1a or stage 1b depending on whether or not it is ulcerated.

Melanoma in situ

Melanoma in situ, or melanocytic intraepithelial neoplasia (MIN), is 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 into the surrounding skin. It’s called a Stage 0 melanoma and it’s sometimes described as precancerous. Lentigo maligna is a type of melanoma in situ.

Melanoma in situ can be cured and there shouldn’t be any risk of it coming back after surgery.