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Skin cancer stages

Making an educated treatment decision begins with the stage, or progression, of the disease. The stage of skin cancer is one of the most important factors in evaluating treatment options. Non-melanoma skin cancers, such as basal cell carcinomas rarely spread and may not be staged. The chance that squamous cell carcinomas will spread is slightly higher.

The American Joint Commission on Cancer has developed a uniform system for describing the stages of skin cancer. This system allows doctors to determine how advanced a skin cancer is, and to share that information with each other in a meaningful way. This system, known as the TNM system, is composed of three key pieces of information:

T (tumor): This describes the tumor’s size, location and how deep it has grown into the skin.

N (node): This indicates whether or not cancer cells have spread to nearby lymph nodes, or the channels connecting the lymph nodes.

M (metastasis): This refers to whether the cancer cells have spread to distant organs.

Basal cell carcinoma stages

There are certain features that are considered to make the cancer at higher risk for spreading or recurrence, and these may also be used to stage basal cell carcinomas. These include:

  • Greater than 2 mm in thickness
  • Invasion into the lower dermis or subcutis layers of the skin
  • Invasion into the tiny nerves in the skin
  • Location on the ear or on a hair-bearing lip

After the TNM components and risk factors have been established, the cancer is given a stage. For basal cell carcinoma staging, the factors are grouped and labeled 0 to 4. The characteristics and stages of basal cell carcinoma are:

Stage 0: Also called carcinoma in situ, cancer discovered in this stage is only present in the epidermis (upper layer of the skin) and has not spread deeper to the dermis.

Stage I (stage 1 basal cell carcinoma): The cancer is less than 2 centimeters, about 4/5 of an inch across, has not spread to nearby lymph nodes or organs, and has one or fewer high-risk features.

Stage II (stage 2 basal cell carcinoma): The cancer is larger than 2 centimeters across, and has not spread to nearby organs or lymph nodes, or a tumor of any size with 2 or more high-risk features.

Stage III (stage 3 basal cell carcinoma): The cancer has spread into facial bones or 1 nearby lymph node, but not to other organs.

Stage IV (stage 4 basal cell carcinoma): The cancer can be any size and has spread (metastasized) to 1 or more lymph nodes which are larger than 3 cm and may have spread to bones or other organs in the body.

Squamous cell carcinoma stages

There are certain features that are considered to make the cancer at higher risk for spreading or recurrence, and these may also be used to stage squamous cell carcinomas. These include:

  • Greater than 2 mm in thickness
  • Invasion into the lower dermis or subcutis layers of the skin
  • Invasion into the tiny nerves in the skin
  • Location on the ear or on a hair-bearing lip

After the TNM components and risk factors have been established, the cancer is assigned to one of the five squamous cell carcinoma stages, which are labeled 0 to 4. The characteristics and stages of squamous cell cancer are:

Stage 0: Also called carcinoma in situ, cancer discovered in this stage is only present in the epidermis (upper layer of the skin) and has not spread deeper to the dermis.

Stage I (stage 1 squamous cell carcinoma): The cancer is less than 2 centimeters, about 4/5 of an inch across, has not spread to nearby lymph nodes or organs, and has one or fewer high-risk features.

Stage II (stage 2 squamous cell carcinoma): The cancer is larger than 2 centimeters across, and has not spread to nearby organs or lymph nodes, or a tumor of any size with 2 or more high risk features.

Stage III (stage 3 squamous cell carcinoma): The cancer has spread into facial bones or 1 nearby lymph node, but not to other organs.

Stage IV (stage 4 squamous cell carcinoma): The cancer can be any size and has spread (metastasized) to 1 or more lymph nodes which are larger than 3 cm and may have spread to bones or other organs in the body.

Next topic: How is skin cancer diagnosed?