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 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 a similar fashion.

How is the melanoma 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:

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

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

  • M (metastasis): Refers to whether the melanoma has spread to distant organs, as well as on levels of LDH, a substance in the blood.

Melanoma may be staged before surgery (clinical staging), based on physical exam and imaging results. It can also be staged after surgery (pathologic staging), in which the clinical information will be combined with information gained from biopsies. Because it uses more information, pathologic cancer staging is the most accurate.

The stages of melanoma are:

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

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

  • Stage II: The cancer cells have grown deeper into the skin, or have more high-risk features, but have not spread to the lymph nodes or beyond.

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

  • Stage IV: Stage IV melanoma (also known as metastatic melanoma) means the 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. Your evaluation, as well as your medical history and other relevant factors, will be carefully reviewed by your care team to develop a customized melanoma treatment plan for you.