Stages of Melanoma

If you are diagnosed with melanoma, your doctor will determine the stage (or extent) of the disease. Staging is a way of determining how much disease is in the body and where it has spread. This information is important because it helps our Melanoma Program team determine the best type of treatment for you and the outlook for your prognosis.

Melanoma staging is based on:

  • Location(s) of the melanoma
  • Primary melanoma tumor thickness as well as other microscopic features
  • If it has spread to nearby lymph nodes, and if so, how many and what size
  • If it has metastasized [link to metastatic page] to other parts of the body
  • Blood tests may also be used to evaluate the extent of melanoma

Stages 1 and 2 are localized to the primary tumor site with no indication of spread to other locations. These first two stages are subdivided based upon the characteristics of the primary tumor, for example, its thickness.

In stages 3 and 4 the melanoma has spread from its origin either to local lymphatic channels or lymph nodes (Stage 3) in the same region or through the blood stream to distant sites (Stage 4).

Stage 0 (Melanoma in situ):

  • The abnormal cells are limited to the uppermost layer of the skin, where they belong.
  • If completely removed, these tumors cannot spread to other parts of the body

Stage 1A: Melanoma:

  • Is less than 1 millimeter thick
  • No ulceration and no dividing cells (mitoses).

Stage 1B: Melanoma:

  • Is less than 1 millimeter thick and with ulceration and/or has at least one mitosis (dividing cell) per square millimeter or one to two millimeters thick without ulceration

Stage 2A: Melanoma is either:

  • 1 to 2 millimeters thick with ulceration or,
  • 2 to 4 millimeters thick with no ulceration

Stage 2B: Melanoma is either:

  • 2 to 4 millimeters thick with ulceration or,
  • More than 4 millimeters thick without ulceration

Stage 2C: Melanoma is:

  • More than 4 millimeters thick with ulceration

Stage3: Melanoma:

  • Has spread through the lymph system (satellites and/or in-transit metastasis) or directly into the regional lymph nodes (lymph nodes that receive lymph drainage from primary tumor site)
  • Has not spread to distant organs

Stage 4: Melanoma has:

  • Spread (metastasized) through the blood stream to distant sites in the body