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Skin cancer stages

This page was reviewed under our medical and editorial policy by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on April 7, 2022.


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 Committee 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 basal cell carcinoma: 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 1 basal cell carcinoma: In stage 1, 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 2 basal cell carcinoma: In stage 2, 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 3 basal cell carcinoma: In stage 3, the cancer has spread into facial bones or 1 nearby lymph node, but not to other organs.

Stage 4 basal cell carcinoma: In stage 4, 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

As with basal cell carcinoma, certain features of squamous cell carcinoma raise the risk that the cancer will spread or recur, and those factors are often key in determining the stage of squamous cell carcinomas. These features 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 squamous cell carcinoma: 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. This stage of squamous cell carcinoma is also called Bowen's disease of the skin, which appears as red or pink scaly patches, mostly on skin that's often exposed to the sun.

Stage 1 squamous cell carcinoma: In stage 1, 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 squamous cell carcinoma: In stage 2, 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 squamous cell carcinoma: In stage 3, the cancer has spread into facial bones or 1 nearby lymph node, but not to other organs.

Stage squamous cell carcinoma: In stage 4, 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.

Stages of skin cancer and treatment

Treatment options vary depending on the stage of your skin cancer. They can range from topical treatments applied directly to the skin for early-stage cancers to more internal treatments such as radiation, chemotherapy and surgery for advanced-stage cancers.

Doctors generally recommend the least invasive regimens appropriate for a particular case, in an attempt to reduce side effects and maintain quality of life as much as possible during treatment.

Beyond stage, other factors that may affect treatment decisions include:

  • Tumor size
  • Tumor location
  • The way cancer cells appear under a microscope
  • The patient’s immune system

In general, stage 0 squamous or basal cell cancers may be removed via a surgical procedure or destroyed using other noninvasive methods, such as topical chemotherapy sometimes combined with photodynamic therapy (light therapy).

If surgery is needed, procedures for basal cell and squamous cell skin cancers most often include:

  • Cryosurgery: a device is used to freeze and kill cancer cells
  • Simple excision: the tumor and the surrounding skin are cut away
  • Mohs micrographic surgery: layers of the skin are removed in stages while the cells are tested to make sure all of the cancer is removed
  • Curettage and electrodessication (electrosurgery): a spoon-shaped knife scoops away the cancerous cells and surrounding tumor, then electricity is used to further destroy cancer cells and stop bleeding

If the tumor is large or has spread to lymph nodes, bones or other organs, systemic treatments can help destroy more cancer cells beyond the tumor. These typically include:

  • Radiation therapy: high-energy X-rays destroy cancer cells
  • Immunotherapy: biological treatments help your immune system harm cancer cells
  • Targeted therapy: drugs target specific cancer cells in the body

Systemic chemotherapy (which involves administering drugs to destroy fast-growing cancer cells), is rarely used for basal cell carcinomas, but in some cases, it may be recommended after other therapies for patients with advanced squamous cell skin cancer.

Next topic: How is skin cancer diagnosed?

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