Stage I Melanoma

Stage I melanoma is defined as a melanoma that is up to 2 mm thick. A Stage I melanoma may or may not have ulceration. There is no evidence the cancer has spread to lymph nodes or distant sites (metastasis). There are two subclasses of Stage I melanoma: 1A, 1B.

Stage 1: Melanoma "localized tumor"

Subclasses 1A, 1B

Differentiated by tumor thickness (Breslow Depth)

It hasn’t spread to nearby lymph nodes or distant sites

Risk: Low

Stage I Melanomas Are Defined by 3 Primary Characteristics:

  • Tumor thickness (Breslow Depth): how deeply the tumor has penetrated the skin. Thickness is measured in millimeters (mm). For example:
    • 1 mm = .04 inch, or less than 1/16 inch (about equal to the edge of a penny)
    • 2 mm = between 1/16 and 1/8 inch (about equal to the edge of a nickel)
    • 4 mm = between 1/8 and 1/4 inch (about equal to the edges of two nickels)
  • Ulceration: when the epidermis (or top layer of skin)  that covers a portion of the primary melanoma is not intact. Ulceration can only be seen under a microscope, not by the naked eye.
  • Mitotic Count (Rate): describes how quickly the tumor cells are dividing. Mitotic count is calculated by a pathologist who counts the average number of actively dividing cells in the biopsy sample.

There Are 2 Subclasses of Stage I Melanoma

Stage 1A (T1aNOMO)

T1a: Tumor is no more than 1.0mm thick, no ulceration, and mitotic count is less than 1/mm.2
NO: No spread to nearby lymph nodes.
MO: No evidence of metastasis to distant sites.

Stage 1B (T1bNOMO or T2aNOMO)

T1b: Tumor is no more than 1.0mm thick, with ulceration, or a mitotic count equal or greater than 1/mm.2
T2a: Tumor is 1.01-2.0mm thick with no ulceration.
NO: No spread to nearby lymph nodes.
MO: No evidence of metastasis to distant sites.

Risk: Patients with Stage I melanoma are considered low risk for local recurrence or for regional and distant metastases. Keep in mind that the statistics shown for survival are averages; everyone’s cancer and survival rate is based on many factors and determined on an individual basis.

Learn about Stage I follow-up

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