Melanoma Skin Cancer Stages

After someone is diagnosed with melanoma, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.

The earliest stage melanomas are called stage 0 (carcinoma in situ), and then range from stages I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. And within a stage, an earlier letter means a lower stage. Although each person’s cancer experience is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way.

How is the stage determined?

The staging system most often used for melanoma is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:

The extent of the tumor (T): How deep has the cancer grown into the skin? Is the cancer ulcerated?

Tumor thickness: The thickness of the melanoma is called the Breslow measurement. In general, melanomas less than 1 millimeter (mm) thick (about 1/25 of an inch) have a very small chance of spreading. As the melanoma becomes thicker, it has a greater chance of spreading.

Ulceration: Ulceration is a breakdown of the skin over the melanoma. Melanomas that are ulcerated tend to have a worse outlook.

The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?

The spread (metastasis) to distant sites (M): Has the cancer spread to distant lymph nodes or distant organs such as the lungs or brain?

Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced. Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage. For more information see Cancer Staging.

The staging system in the table below uses the pathologic stage (also called the surgical stage). It is determined by examining tissue removed during an operation. Sometimes, if surgery is not possible right away or at all, the cancer will be given a clinical stage instead. This is based on the results of a physical exam, biopsy, and imaging tests. The clinical stage will be used to help plan treatment. Sometimes, though, the cancer has spread further than the clinical stage estimates, and may not predict the patient’s outlook as accurately as a pathologic stage.

There are both clinical and pathologic staging systems for melanoma. Since most cancers are staged with the pathologic stage, we have included that staging system below. If your cancer has been clinically staged, it is best to talk to your doctor about your specific stage.  

The table below is a simplified version of the TNM system. It is based on the most recent AJCC system, effective January 2018. It’s important to know that melanoma cancer staging can be complex. If you have any questions about the stage of your cancer or what it means, please ask your doctor to explain it to you in a way you understand.

AJCC Stage

Melanoma Stage description*

0

The cancer is confined to the epidermis, the outermost skin layer.

It has not spread to nearby lymph nodes or distant sites. This stage is also known as melanoma in situ.

I

 

The cancer is no more than 2mm (2/25 of an inch) thick and might or might not be ulcerated. It has not spread to nearby lymph nodes or to distant sites.

 

II

The cancer is at least 1.01 mm and may be thicker than 4.0 mm. It might or might not be ulcerated. It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

 

IIIA

The cancer is no more than 2.0 mm thick. It might or might not be ulcerated. It has spread to 3 or less lymph node(s), but it is so small that it is only seen under the microscope. It has not spread to distant sites.

 

IIIB

 

There is no sign of the primary cancer AND:

  • Has spread to only one lymph node OR
  • Has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (without reaching the lymph nodes).

It has not spread to distant sites.

OR

The cancer is no more than 4.0 mm thick. It might or might not be ulcerated AND:  

  • Has spread to only one lymph node OR
  • Has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (without reaching the lymph nodes) OR
  • Has spread to 2 or 3 lymph nodes.

It has not spread to distant sites.

IIIC

There is no sign of the primary cancer AND:

  • Has spread to one or more lymph nodes OR
  • Has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (without reaching the lymph nodes) OR
  • Has spread to any lymph nodes that are clumped together.

It has not spread to distant sites.

OR

The cancer is no more than 4.0 mm thick. It might or might not be ulcerated AND:

  • Has spread to one or more lymph nodes OR
  • Has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (without reaching the lymph nodes) OR
  • Has spread to lymph nodes that are clumped together.

It has not spread to distant sites.

OR

The cancer is between 2.1 and 4.0mm OR thicker than 4.0 mm. It might or might not be ulcerated AND:

  • Has spread to one or more lymph nodes OR
  • Has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (without reaching the lymph nodes) OR
  • Has spread to lymph nodes that are clumped together.

It has not spread to distant sites.

OR

The cancer is thicker than 4.0 mm and is ulcerated AND:

  • Has spread to no more than 3 lymph nodes OR
  • Has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (without reaching the lymph nodes).

It has not spread to distant sites.

IIID

The cancer is thicker than 4.0 mm and is ulcerated AND:

  • Has spread to 4 or more lymph nodes OR
  • Has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (without reaching the lymph nodes) OR
  • Has spread to lymph nodes that are clumped together.

It has not spread to distant sites.

IV

The cancer can be any thickness and might or might not be ulcerated. It might or might not have spread to nearby lymph nodes. It has spread to distant lymph nodes or organs such as the lungs, liver or brain.

 

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

American Joint Committee on Cancer. Melanoma of the Skin. In: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer; 2017:563.

Last Medical Review: December 14, 2017 Last Revised: December 14, 2017

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