Melanoma: Stages

The stage of a cancer is how much and how far the cancer has spread in your body. Your health care provider uses exams and tests to find out the size of the cancer and where it is. He or she can also see if the cancer has grown into nearby areas, and if it has spread to other parts of your body. The stage of a cancer is one of the most important things to know when deciding how to treat the cancer.

The TNM system

Doctors use different systems to measure the thickness of a melanoma and to stage the disease. These systems summarize the extent of your cancer. The American Joint Committee on Cancer (AJCC) staging system is used most often for melanoma. It is called the TNM system.

  • The T stands for tumor. This category is based on the melanoma's thickness and whether it is ulcerated. The thickness of the melanoma is called the Breslow measurement. The term ulcerated means that the layer of skin covering the melanoma is gone. There may be bleeding with ulceration.

  • N stands for lymph nodes. Lymph nodes are small groups of cells that help the body fight infections. This category shows whether the melanoma has spread to nearby lymph nodes.

  • M stands for metastasis. This category tells whether the cancer has spread to distant organs.

Understanding the numbers used in staging

Stages are named using a combination of 0 or the Roman numerals I to IV. The letters A through C are for substages. Lower stage cancers have a better outlook.

Stage 0. The melanoma is only in the top layer of skin (epidermis). This is also called melanoma in situ. In situ means the cancer has remained confined, and has not invaded deeper into the skin.

Stage IA. The tumor is in the epidermis and the upper part of the layer of skin under the epidermis (dermis). It is no more than 1 millimeter thick.

Stage IB. The tumor is 1 to 2 mm thick, with no ulceration.

Stage IIA. The tumor is 1 to 2 mm thick with ulceration. Or it is 2 to 4 mm thick with no ulceration.

Stage IIB. The tumor is between 2 and 4 mm thick, with ulceration. Or it is more than 4 mm thick with no ulceration.

Stage IIC. The tumor is thicker than 4 mm and is ulcerated.

Stage III.Stage III is divided into stages IIIA, IIIB, IIIC and IIID depending on the thickness of the tumor and varying degrees of lymph node involvement.

  • 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 1 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 1 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 1 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 1 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 1 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.

Stage IV. The tumor has spread to distant lymph nodes, skin, or other organs in the body.

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