Basal and Squamous Cell Skin Cancer Stages

After someone is diagnosed with cancer, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Staging is determined by examining tissue removed during an operation and sometimes imaging tests and physical exams (described in Tests for Basal and Squamous Cell Skin Cancers).

Determining the stage of basal cell skin cancers is rarely needed, because these cancers are almost always cured before they spread to other parts of the body.

Squamous cell skin cancers are more likely to spread (although this risk is still small), so determining the stage can be more important, particularly in people who are at higher risk. This includes people with weakened immune systems, such as those who have had organ transplants and people infected with HIV, the virus that causes AIDS. Most squamous cell skin cancers occur in the head and neck region and tend to have a higher risk of recurring (coming back) or spreading compared to those in other locations.

The most recent American Joint Committee on Cancer (AJCC) staging system, effective January 2018, applies to squamous cell and basal cell carcinoma skin cancers of the head and neck area (lip, ear, face, scalp and neck). If your skin cancer is in the head and neck area, talk to your doctor about your specific stage. 

How is the stage determined?

The system most often used to stage basal and squamous cell skin cancers of the head and neck area is the American Joint Commission on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:

  • The extent (size) of the tumor (T): Where is the cancer located? How large is the cancer? Has it grown into nearby structures or tissues?
  • The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?
  • The spread (metastasis) to distant sites (M): Has the cancer spread to other parts of the body?

Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced.

Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage. The earliest stage of skin cancer is stage 0 (also called carcinoma in situ, or CIS). The other stages range from I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more.

Cancer staging can be complex, so ask your doctor to explain it to you in a way you understand. For more information see Cancer Staging.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

American Joint Committee on Cancer. Cutaneous Squamous Cell Carcinoma of the Head and Neck. In: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer; 2017: 171. 

Last Medical Review: December 20, 2017 Last Revised: December 20, 2017

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