Stages of melanoma skin cancer

Staging describes or classifies a cancer based on how much cancer there is in the body and where it is when first diagnosed. This is often called the extent of cancer. For melanoma skin cancer, the healthcare team uses information from tests to find out the thickness of the tumour, if the skin over the tumour is broken with an open wound (called ulceration), if the cancer has spread from where it first started and where the cancer has spread. Doctors use the stage to plan treatment and estimate the outcome (prognosis).

The most common staging system for melanoma is the TNM system. For melanoma there are 5 stages – stage 0 followed by stages 1 to 4. Often the stages 1 to 4 are written as the Roman numerals I, II, III and IV. Generally, the higher the stage number, the more the cancer has spread.

When describing the stage, doctors often use the words early stage, locoregional or metastatic.

Early stage means that the cancer is only in the skin where it started and has not spread to other parts of the body. It includes stage 0, stage 1A, stage 1B, stage 2A, stage 2B and stage 2C melanomas.

Locoregional means the cancer has spread to nearby lymph nodes or to nearby areas of skin or lymph vessels. It includes stage 3 melanomas.

Metastatic means that the cancer is in a part of the body far away from where it started, such as in the lungs or the brain. It includes stage 4 melanomas.

Most often, doctors will give melanoma a pathological stage. The doctor will do surgery to remove the tumour, to take a sample from the lymph nodes that cancer is likely to have spread to (called sentinel lymph node biopsy) or to remove lymph nodes (called lymph node dissection). Doctors will examine the tumour and lymph nodes under a microscope to determine the pathological stage. This gives them a more complete idea of the extent of cancer in the body.

If surgery can't be done, the cancer will be given a clinical stage. Clinical stage uses information from physical exams, biopsies and imaging tests. Because the cancer may have spread farther than what the clinical stage estimates, it may not give doctors the most accurate information for a prognosis.

Talk to your doctor if you have questions about the stage you were given. Find out more about staging cancer.

Cancer cells are only in the top, or outer, layer of the skin (epidermis). Some doctors describe melanoma in situ as a precancerous condition of the skin. The tumour hasn't spread into the deeper layer of the skin (dermis) and cancer hasn't spread to the lymph nodes.

The tumour is less than 1 mm thick and may be ulcerated.

The cancer hasn't spread to the lymph nodes.

The tumour is 1 mm to 2 mm thick and isn't ulcerated.

The cancer hasn't spread to the lymph nodes.

The tumour is 1 mm to 2 mm thick and ulcerated.

Or the tumour is 2 mm to 4 mm thick and not ulcerated.

The cancer hasn't spread to the lymph nodes.

The tumour is 2 mm to 4 mm thick and ulcerated.

Or the tumour is more than 4 mm thick and not ulcerated.

The cancer hasn't spread to the lymph nodes.

The tumour is more than 4 mm thick and is ulcerated.

The cancer hasn't spread to the lymph nodes.

The cancer has spread to 1 or more lymph nodes near where it started (called regional lymph nodes).

A pathologist will examine the tumour and lymph nodes after they are removed with surgery. Based on this exam, the pathologist will give stage 3 melanoma a pathological stage of 3A, 3B, 3C or 3D depending on:

• the number of lymph nodes that contain cancer
• the amount of cancer in the lymph nodes
• if the cancer has spread to nearby areas of skin (called satellite tumours) or lymph vessels (called in-transit metastasis)

The cancer has spread to other parts of the body (called distant metastasis), such as to the lungs, liver or brain. Stage 4 melanoma may also be called metastatic melanoma.

Recurrent melanoma means that the cancer has come back after it has been treated.

Locally recurrent melanoma means that it came back in the same place as or close to where it first started.

Distant recurrence means that melanoma came back in a different part of the body from where it started.