Non-melanoma skin cancer

You are here: 

Risk groups for non-melanoma skin cancer

Doctors classify most non-melanoma skin cancers into risk groups that are based on several prognostic factors, including the size of the cancer and where it is located. The risk groups allow the doctor to estimate the chance that the cancer will come back (recur). Doctors also use the risk groups to help plan the best treatment.

Basal cell carcinoma (BCC)

The prognosis is usually very good for BCC because it can be found and treated early. BCC is classified as low or high risk based on its risk of coming back.

Low-risk BCC

BCC is put in the low-risk group when:

  • It is on the trunk of the body, arms, legs, cheeks, forehead, temples, scalp, neck or chin.
  • It is 2 cm or smaller.
  • It is nodular or superficial.
  • It is a primary cancer that has not come back after treatment.
  • The edge of the cancerous area is clear and smooth.
  • There is no cancer in or around nerves.

High-risk BCC

BCC is put in the high-risk group when:

  • It is on the eyelids, nose, ears or skin around the eyes.
  • It is larger than 2 cm.
  • It is an aggressive subtype, such as infiltrative, morpheaform or micronodular.
  • It has come back after treatment.
  • The edge of the cancerous area is uneven.
  • The cancer has grown into or around nerves.

Squamous cell carcinoma (SCC)

SCC is classified as low or high risk based on its risk of coming back.

Low-risk SCC

SCC is put in the low-risk group when:

  • It is anywhere on the skin except for the ears, lips and scalp.
  • It is smaller than 2 cm.
  • It is less than 2 mm deep or Clark’s classification level I, II or III.
  • The cancer is only in the top or outer layer of the skin (SCC in situ).
  • It is low grade.
  • It is a primary cancer that has not come back after treatment.
  • There is no cancer in or around nerves.

High-risk SCC

SCC is put in the high-risk group when:

  • It is on the ears, lips or scalp.
  • It is 2 cm or larger.
  • It 2 mm or more deep or Clark’s classification level IV or V.
  • It is high grade.
  • It is growing quickly.
  • It has come back after treatment.
  • The person has a weakened immune system (immunosuppression).
  • The cancer has grown into or around nerves.

Clark's classification

A system used to describe how deep a cancerous skin tumour goes into the layers of the skin.

Clark’s classifications (levels I through V) are based on the layer of skin the tumour grows into.

Also called Clark’s levels.

Clark's classification

A system used to describe how deep a cancerous skin tumour goes into the layers of the skin.

Clark’s classifications (levels I through V) are based on the layer of skin the tumour grows into.

Also called Clark’s levels.

Stories

Tyler Cook This research saved my life and my sister’s life. Without it, stomach cancer would have wiped out most of our family.

Read Tyler's story

Making progress in the cancer fight

Icon - arrow

The 5-year cancer survival rate has increased from 25% in the 1940s to 60% today.

Learn more