Stages of Melanoma

Once someone has been 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 cancer describes how much cancer is in the body. It helps determine how serious the cancer is and the best way to treat it.


The earliest stage melanomas are stage 0 (melanoma in situ), and then range from stages I through IV. Some stages are split further, using capital letters (A, B, etc.). As a rule, the lower the number, the less cancer has spread. A higher number, such as stage IV, means cancer has spread to other parts of the body. Within each stage, an earlier letter means a lower stage. Although each person's cancer experience is unique, cancers with similar stages tend to have a comparable outlook and are often treated similarly.

How is the melanoma stage determined?

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

  • T (tumor): Describes the thickness of the tumor, or how deep it has grown into the skin. The thickness, also known as the Breslow measurement, is an significant factor in predicting whether or not a tumor has spread to other parts of the body. The thicker the melanoma, the greater the odds of it spreading. The rate at which the tumor cells divide (also known as the mitotic rate), and the presence or absence of ulceration (an open, bleeding sore) are also considered when determining the T category.

  • N (node): Indicates whether or not the melanoma has spread to nearby lymph nodes or the avenues connecting them.

  • M (metastasis): Refers to whether the melanoma has spread to distant organs or the blood.

Melanomas staged before surgery are clinically staged based on physical exam and imaging results. Melanomas staged after surgery are pathologically staged. This means the clinical information is combined with information gained from biopsies. Because it uses more information, pathologic cancer staging is the most accurate.

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The stages of melanoma are:

  • Stage 0: Cancer cells are confined to the epidermis (the top layer of skin) and have not spread. At this stage, the cancer can usually be handled by surgery alone.

  • Stage I: Cancer cells have grown deeper into the skin, but have not spread to the lymph nodes or other parts of the body.

  • Stage II: Cancer cells have grown deeper into the skin, or have more high-risk characteristics, but have not spread to the lymph nodes or other distant organs.

  • Stage III: Cancer cells have spread to nearby lymph nodes, but not to distant organs.

  • Stage IV: Also known as metastatic melanoma, Stage IV means cancer cells have spread beyond the skin and regional lymph nodes to distant organs such as the liver, lungs or brain, or distant lymph nodes and areas of the skin. Many factors, including your evaluation and medical history, will be carefully reviewed by your care team to develop a customized melanoma treatment plan that is right for you.