Non-melanoma skin cancer

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Staging non-melanoma skin cancer

Staging is a way to describe or classify a cancer based on the extent of cancer in the body. Extent includes the size of the tumour and where the cancer is. Your healthcare team uses the stage to plan treatment and estimate your prognosis.

The staging system used for non-melanoma skin cancer is the TNM system. Each stage is given a number from 0 to 4. Stages 1 to 4 are usually given as the Roman numerals I, II, III and IV. Generally, the higher the number, the more the cancer has spread.

Even though a staging system has been developed for non-melanoma skin cancer, doctors don’t usually use it. Since most non-melanoma skin cancers are found early and don’t spread to other parts of the body, staging is not needed. Doctors often classify non-melanoma skin cancer into risk groups instead of staging the cancer.

Merkel cell carcinoma is staged differently than other non-melanoma skin cancers. Find out more about staging for Merkel cell carcinoma.

TNM descriptions

T describes the size of the primary tumour. It also describes if the tumour has grown deeper into the skin or into other tissues around where the cancer started. T is usually given as a number from 1 to 4. A higher number means that the tumour is larger and has more high-risk features.

N describes whether or not cancer has spread to lymph nodes near where the cancer started. N0 means the cancer hasn’t spread to any nearby lymph nodes. N1, N2 or N3 means cancer has spread to lymph nodes. N1 to N3 can also describe the number of lymph nodes that contain cancer, as well as their size and where they are.

M describes whether or not the cancer has spread to other parts of the body (metastases). M0 means that cancer has not spread to other parts of the body. M1 means that it has spread to other parts of the body.

High-risk tumour features

Along with the size of the tumour, doctors will consider other factors to help stage the cancer. Some features of non-melanoma skin cancer are associated with a higher risk of the cancer coming back after it has been treated (recurrence) or spreading. The following are high-risk features for non-melanoma skin cancer:

  • The tumour is more than 2 mm deep using Breslow’s classification.
  • The tumour is level IV or higher using Clark’s classification.
  • The cancer is on the ears or lips.
  • The cancer has grown into or around nerves (called perineural invasion).
  • The cancer is high grade.

Stage 0 (or carcinoma in situ)

TNMDescription

Tis

N0

M0

The cancer cells are only in the top or outer layer of the skin (epidermis). Squamous cell carcinoma in situ is also called Bowen’s disease.

Stage I

TNMDescription

T1

N0

M0

The tumour is 2 cm or smaller. It has no high-risk features or 1 high-risk feature.

Stage II

TNMDescription

T2

N0

M0

The tumour is larger than 2 cm, or the tumour is any size with 2 or more high-risk features.

Stage III

TNMDescription

T3

N0

M0

The tumour has grown into bone of the upper or lower jaw (maxilla or mandible), an eye socket (orbit) or the side of the skull (temporal bone).

T1, T2 or T3

N1

M0

The tumour is any size and may have high-risk features. The tumour may have grown into bone of the jaw, an eye socket or the side of the skull.

The cancer has spread to 1 lymph node that is 3 cm or smaller, and it is on the same side of the body where the cancer started.

Stage IV

TNMDescription

T1, T2 or T3

N2

M0

The tumour is any size and may have high-risk features. The tumour may have grown into bone of the jaw, an eye socket or the side of the skull.

The cancer has spread to 1 lymph node that is larger than 3 cm but smaller than 6 cm, and it is on the same side of the body where the cancer started.

Or the cancer has spread to many lymph nodes and none of them are larger than 6 cm.

any T

N3

M0

The tumour is any size and may have high-risk features. The tumour may have grown into bone.

The cancer has spread to 1 or more lymph nodes that are 6 cm or larger.

T4

any N

M0

The tumour has grown into any bone.

The cancer has spread to at least 1 lymph node.

any T

any N

M1

The tumour is any size and may have high-risk features. The tumour may have grown into bone.

The cancer has spread to at least 1 lymph node.

The cancer has spread to other parts of the body (called distant metastasis).

Recurrent non-melanoma skin cancer

Recurrent non-melanoma skin cancer means that the cancer has come back after it has been treated. If it comes back in the same place that the cancer first started, it’s called local recurrence. If it comes back in tissues or lymph nodes close to the primary tumour, it’s called regional recurrence. In rare cases, it can come back in another part of the body. That is called a distant metastasis or a distant recurrence.

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