Melanoma Staging: What it Means and Reveals

Definition and Prognosis of Stage I to Stage IV Melanoma

stages of melanom
Stages of melanoma. Istockphoto.com/Stock Photo©alexluengo

What is Melanoma Staging?

Melanoma staging is the process used to determine the size of a melanoma tumor and where and how far it has spread. Melanoma is divided in stages from stage 0, which is the smallest, to stage IV, which is the highest stage. This melanoma image gallery shows some of the stages in photos.

Why is Melanoma Staging So Important?

Staging helps your healthcare team plan the appropriate treatment.

Melanoma, the most aggressive form of skin cancer, is always staged. Determining the stage of a melanoma is one of the most important factors in choosing the best treatment options (links to treatments based on stage are listed below.)

TNM Staging of Melanoma

Health professionals have come up with various methods for staging cancers. This article uses the 2009 TNM System recommended by the American Joint Commission on Cancer, the most widely used staging system in the world. Your doctor may also assign a Clark and Breslow number — measurements of tumor penetration and thickness, respectively — to further stage your melanoma and determine your prognosis.

In the TNM system, the letter T, N, and M refer to:

  • T = tumor. T is followed by a number corresponding to tumor thickness.
  • N = node. N is followed by a number corresponding to the extent of lymph node involvement.
  • M = metastasis (distant spreading). M is followed by a number corresponding to the extent of metastasis.

    In addition, the "T" may be followed an "a" signifying no ulceration, or a "b" signifying ulceration. Ulceration, which indicates more severe disease and is identified under the microscope, occurs when melanoma invades the overlying skin.

    In general, the thicker the lesion and the farther the cancer has spread, the higher the assigned stage.

    The higher the stage, the worse the long-term outlook. The earliest melanomas, which do not penetrate beneath the surface of the skin and are known as melanoma in situ, are highly curable and are called stage 0 or not given a stage. (This article discusses in situ cancer.) Subsequent stages are as follows:

    Stage I. Cure rates are excellent with surgical removal, since they are least likely to have spread.

    • Stage 1A (T1aN0M0). Tumor has not spread to the nodes. It is less than 1 mm and is not ulcerated. Five-year survival is 95 percent.
    • Stage IB (T1bN0M0 or T2aN0M0). Tumor has not spread to the nodes. It is less than 1 mm, but is ulcerated, or the tumor is between 1.01 and 2 mm but is not ulcerated. Five-year survival is 89-91 percent.
    • However, a tumor can be <1.0 mm and not ulcerated but still not be Stage IA -- if it has a higher Clark level of invasion. Similarly, a tumor can be T1b and < 1.0 mm without ulceration if it has an advanced Clark level.

    Stage II. Melanomas can be cured, but the success rate lags behind that of Stage I because a small number of cancer cells may have spread to distant sites.

    In addition to surgery, other forms of therapy may be recommended.

    • Stage IIA (T2bN0M0 or T3aN0M0). Tumor has not spread to the nodes. It is between 1.01 and 2 mm and is ulcerated, or it is 2.01 to 4 mm without ulceration. Five-year survival is 77-79 percent.
    • Stage IIB (T3bN0M0 or T4aN0M0). Tumor has not spread to the nodes. It is between 2.01 and 4 mm and is ulcerated or greater than 4 mm without ulceration. Five-year survival is 63-67 percent.
    • Stage IIC (T4bN0M0). Tumor has not spread to the nodes. It is greater than 4 mm and is ulcerated. Five-year survival is 45 percent.

    Stage III. Since the tumor has started to metastasize, the survival rate for these stages is lower than the earlier ones.

    • Stage IIIA (T1a-4a, N1a-N2a, M0). The tumor is not ulcerated. It has spread to up to 3 nodes, but they are not enlarged. The nodal spread is evident only on microscopic examination, not on clinical examination. Five-year survival is 63-69 percent.
    • Stage IIIB. This is a complicated stage with many possible scenarios:
      1. T1b-T4b, N1a-N2a. The tumor is ulcerated. It has spread to up to 3 nodes, but they are not enlarged. The nodal spread is evident only on microscopic examination, not on clinical examination.
      2. T1a-T4a, N1b-N2b. The tumor is not ulcerated. It has spread to up to 3 nodes, and the nodes are enlarged because of the melanoma.
      3. T1a/b-T4a/b, N2c. The tumor can be ulcerated or not. The tumor has spread to skin near the melanoma (satellite metastasis) or to nearby lymph channels (in transit metastasis), but the lymph nodes themselves do not contain melanoma.

      Overall five-year survival for this stage is 30-59 percent.

    • Stage IIIC has two possible scenarios:
      1. T1b-T4b, N1b or N2b: The tumor is ulcerated. Melanoma has spread to up to 3 lymph nodes, which are enlarged because of the cancer.
      2. Any T, N3: Tumor can be any thickness and can be ulcerated or not. The melanoma has spread to four or more nearby nodes; or there are clumped (matted) nodes with melanoma in them; or there are satellite or in-transit metastases and spread to nearby lymph nodes.

      Five-year survival is 24-29 percent.

    Stage IV. Associated with metastasis beyond the regional lymph nodes to distant sites in the body such as the lung, liver, or brain, or to distant areas of the skin. Neither the lymph node status nor thickness is considered. 5-year survival ranges from 7 percent to 19 percent.

    A Word About Survival Rates by Stage

    You may feel frightened by the survival rates listed above, but a few words are in order. Statistics are numbers, not people. They predict what the average outcome may be, but say little about how you as an individual will respond to treatment. In addition, treatments are improving. Newer treatments have been approved, and still more are currently being tested in clinical trials. Statistics are often several years old, and may not reflect how someone will respond to treatment today, when better treatments are available.

    Treatment of Melanoma

    As noted earlier, the treatment of melanoma depends very much on the specific stage. The following articles discuss treatment options based on stage:

    The Short Version

    StageCharacteristics
    IATumor ≤ 1.0 mm without ulceration; no lymph node involvement; no distant metastases
    IBTumor ≤ 1.0 mm with ulceration or Clark level IV or V; tumor 1.01-2.0 mm without ulceration; no lymph node involvement; no distant metastases
    IIATumor 1.01-2.0 mm with ulceration; tumor 2.01-4.0 mm without ulceration; no lymph node involvement; no distant metastases
    IIBTumor 2.01-4.0 mm with ulceration
    IIBTumor > 4.0 mm without ulceration; no lymph node involvement; no distant metastases
    IICTumor > 4.0 mm with ulceration; no nodal involvement; no distant metastases
    IIIATumor of any thickness without ulceration with 1 positive lymph node
    IIIBTumor of any thickness without ulceration with 2-3 positive lymph nodes
    IIICTumor of any thickness and 4 more metastatic lymph nodes OR matted nodes OR in-transit met(s)/satellite(s) without metastatic lymph nodes, or combinations of in-transit met(s)/satellite(s), OR ulcerated melanoma and metastatic lymph node(s)
    IVTumor of any thickness with any nodes and any distant metastases

    Sources:

    Balch, C., Gershenwald, J., Soong, S. et al. Final Version of the 2009 AJCC Melanoma Staging and Classification. Journal of Clinical Oncology. 2009. 27(36):6199-6206.

    Mahar, A., Compton, C., Halabi, S. et al. CriticalAssessment of Clinical Prognostic Tools in Melanoma. Annals of Surgical Oncology. 2016. 23(9):2753-61.

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