Skin Cancer Progression And Staging

The process of determining the size and extent of a cancer lesion is called staging. Staging accounts for the size of the lesion and the tissue affected, as well as whether the cancer has spread to other areas of the body. In all types of skin cancer, earlier stages are smaller and more localized, while in later stages, the cancer has unfortunately spread. Skin cancer is more difficult to treat in its later stages, so finding and treating skin cancer early can lead to a better prognosis.

Cancers of the skin are usually categorized into two groups: melanoma skin cancer and nonmelanoma skin cancer (which includes both basal cell and squamous cell carcinomas).

The American Joint Commission on Cancer (AJCC) TNM System

The AJCC TNM staging system is the preferred method for determining the stages of skin cancer. This is particularly true for melanoma, which is more likely to spread to other parts of the body than basal cell carcinoma or squamous cell carcinoma. The TNM system uses a three-part method of classification to describe skin cancer severity:

  • T stands for tumor. The tumor is given a number (0-4) based on how far it penetrates down into the skin. Tumor thickness is measured under a microscope using a micrometer. The rate of cell division is also a factor in assessing the tumor.
  • N stands for the lymph nodes, which are part of the body’s immune system. A number (0-3) represents the degree to which cancer cells have spread to the lymph nodes.
  • M stands for metastasis, which is the spread of cancer cells to distant body parts or organs and the development of secondary tumors in areas such as the lungs or brain.

Nonmelanoma Skin Cancer Staging

Basal cell carcinoma rarely spreads, so it is not always staged according to the AJCC TNM system. However, both basal cell and squamous cell carcinoma may be assigned a TNM stage.

Like melanoma staging, nonmelanoma skin cancer staging uses the numbers 0-4, which describe the lesion in terms of the following considerations:

  • Metastasis (spreading of cancer cell growth) to other areas of the body
  • Penetration into the skin and surrounding tissue, cartilage or bone
  • Surface size.

In nonmelanoma cancer staging, stage 0 identifies precancerous lesions, such as actinic keratosis (a precursor to squamous cell carcinoma). This is also known as carcinoma in situ, and may develop into a skin cancer lesion.

Skin Cancer Staging, Prognosis and Treatment

Overall, skin cancer identified in low stages, or even in stage 0 as a precancerous lesion, has a high survival rate. This is even true for melanoma, which causes the greatest number of skin cancer deaths. In early stages the smaller lesions are confined to the skin, and tend to be easier to remove. Higher stages of both melanoma and nonmelanoma skin cancer are more difficult to treat, because the lesions are larger, and have spread to other areas of the body. Treatment in these cases can involve a combination of surgical removal and other techniques, such as chemotherapy and radiation.


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National Cancer Institute. (2010). Skin cancer treatment (PDQ). Retrieved June 30, 2010, from

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National Cancer Institute. (2003). What you need to know about melanoma. Retrieved June 30, 2010, from