Stages of Melanoma
"Staging" is the process used to determine the size of a melanoma and where and how far it has spread. Staging helps your healthcare team plan:
- The kind of treatment you need
- The likely risk of the melanoma coming back after treatment
- Whether you need tests to see if the melanoma has spread into lymph nodes close to the melanoma.
Melanoma, the most aggressive form of skin cancer, is always staged.
Breslow Thickness
You will often hear your doctors talk about the Breslow thickness of your melanoma. Essentially, the Breslow thickness is defined as the total vertical height (thickness) of the melanoma. It is measured from the very top (called the "granular layer") to the area of deepest penetration in to the skin. The pathologist will look at the melanoma under the microscope after it has been removed and use an instrument called an "ocular micrometer" is used to measure the thickness. In general, the higher the Breslow thickness, the worse the prognosis (keep in mind that these survival rates are averages and may not reflect your individual case). Due to its accuracy in predicting outcomes, the Breslow thickness has been incorporated into the standard TNM staging system for melanoma.
The TNM system.
Several tests and procedures are used to assign T, N, and M categories and a grouped stage. The TNM system for staging contains 3 key pieces of information:
T stands for tumor (how far it has grown within the skin and other factors). The T category is assigned a number (from 0 to 4) based on the tumour’s Breslow thickness (how far down it has grown). It is also assigned a small letter "a" if it is not ulcerated or a "b" if it is ulcerated. Ulceration means the layer of skin covering the melanoma is absent. This is seen under a microscope after a biopsy.
* Tis - melanoma cells are only in the very top layer of the skin surface
* T1 - the melanoma is less than 1 milllimetre thick
* T2 - the melanoma is between 1 mm and 2 mm thick
* T3 - the melanoma is between 2 mm and 4 mm thick
* T4 - the melanoma is over 4 mm thick
N stands for spread to nearby lymph nodes (small bean-shaped collections of immune system cells that help the body fight infections and cancers). The N category is assigned a number (from 0 to 3) based on whether the melanoma cells have spread to lymph nodes or are found in the lymphatic channels connecting the lymph nodes. It is also assigned a small letter: "a" if melanoma cells can only be seen with the microscope or "b" if they can be seen with the naked eye. A letter "c" is assigned if there are very small areas of melanoma in the nearby skin or if the melanoma is in skin lymphatic channels around the tumor (but not in the nodes themselves).
* N0 - there are no melanoma cells in the nearby lymph nodes
* N1 - there are melanoma cells in one lymph node
* N2 - there are melanoma cells in 2 or 3 lymph nodes
* N3 - there are melanoma cells in 4 or more lymph nodes
The M category is based on whether the melanoma has metastasized (spread) to distant organs, which organs it has reached, and sometimes on blood levels of a substance called LDH.
* M1a - melanoma cells have spread to skin in other parts of the body or to lymph nodes far away from the where the melanoma started growing
* M1b- melanoma cells have spread to the lung
* M1c - melanoma cells have spread to other organs or cause high blood levels of LDH
Number Stages of Melanoma (AJCC Stage)
There is an indepth staging system for all scenarios of melanoma. However, for a quick reference it can be simplified into:
- Stages I&II: Melanoma found only at the point it started
- Stage III: Melanoma has spread to the lymph nodes or along the skin towards the lymph nodes
- Stage IV: Melanoma has spread to other distant parts of the body such as lungs, liver, brain and skin.
Stage 0
This means the melanoma cells are only in the top surface layer of skin cells (the epidermis) and have not started to spread into deeper layers. This stage is also called ‘in situ’ melanoma.
Stage Ia
The melanoma is less that 1mm thick. The covering layer of skin over the tumour is not broken – it is not ulcerated. The melanoma is only in the skin and there is no sign that it has spread to lymph nodes or other areas of the body.
Stage Ib
The melanoma is less than 1mm thick and the skin is broken (ulcerated). Or it is between 1 and 2mm and is not ulcerated. The melanoma is only in the skin and there is no sign that it has spread to lymph nodes or other areas of the body
Stage IIa
The melanoma is between 1 and 2mm thick and is ulcerated. Or it is between 2 and 4mm and is not ulcerated. The melanoma is only in the skin and there is no sign that it has spread to lymph nodes or other areas of the body.
Stage IIb
The melanoma is between 2mm and 4mm thick and is ulcerated. Or it is thicker than 4mm and is not ulcerated. The melanoma is only in the skin and there is no sign that it has spread to lymph nodes or other areas of the body.
Stage IIc
The melanoma is thicker than 4mm and is ulcerated. The melanoma is only in the skin and there is no sign that it has spread to lymph nodes or other areas of the body.
Stage IIIa
The melanoma has spread to 1 - 3 lymph nodes near the primary tumour but the nodes are not enlarged and the cells can only be seen under a microscope. The melanoma is not ulcerated and has not spread to other areas of the body.
Stage IIIb
Stage IIIb includes 3 different situations:
• The melanoma has spread to 1 - 3 lymph nodes near the primary tumour but the nodes are not enlarged and the cells can only be seen under a microscope. The melanoma is ulcerated but has not spread to other areas of the body
• The melanoma is not ulcerated. It has spread to 1 - 3 lymph nodes near the primary tumour and the lymph nodes are enlarged. The melanoma has not spread to other areas of the body.
• The melanoma may or may not be ulcerated. It has spread to small areas of skin or lymphatic channels close to the original melanoma but the lymph nodes do not contain melanoma cells. The melanoma has not spread to other areas of the body.
Stage IIIc
Stage IIIc includes 2 different situations:
• The melanoma is ulcerated. It has spread to 1 - 3 lymph nodes near the primary tumour. The lymph nodes contain melanoma cells and are enlarged. The melanoma has not spread to other areas of the body.
• The melanoma may or may not be ulcerated. It has spread to 4 or more nearby lymph nodes. Or to nearby lymph nodes that are clumped together. Or it has spread to nearby skin or lymphatic channels around the original melanoma and nearby lymph nodes. The lymph nodes are enlarged because of the melanoma. The melanoma has not spread to other areas of the body.
Stage IV
These melanomas have spread elsewhere in the body, away from where they started (the primary site) and away from the nearby lymph nodes.
The most common places for melanoma to spread are the lung, liver or brain or to distant lymph nodes or areas of the skin.
In the UK, most melanomas are early stage 1 and are completely cured with surgery and most stage2 tumours can also be cured with surgery
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