Staging for nonmelanoma skin cancer is based on the size of the cancer, lymph node involvement, and the involvement of underlying structures, such as muscle or bone. Staging of nonmelanoma skin cancer has been classified by the American Joint Committee on Cancer (AJCC).¹

• TX: Primary tumor cannot be assessed.
• T0: No evidence of primary tumor.
• Tis: Cancer at this stage is contained in the skin lesion (in situ).
• T1: Tumor is 2 cm (0.8 in.) or smaller.
• T2: Tumor is larger than 2 cm (0.8 in.) but not larger than 5 cm (2 in.).
• T3: Tumor is larger than 5 cm (2 in.).
• T4: Tumor size varies but tumor has spread deeply into muscle, cartilage, or bone.

After the tumor (T) is staged, the TNM system stages lymph node involvement (N) to help determine the treatment options at each stage. Lymph node involvement is staged in the following way:

• NX: Nearby (regional) lymph nodes cannot be assessed.
• N0: Cancer has not spread (metastasized) to nearby lymph nodes.
• N1: Cancer has spread to nearby lymph nodes.

The last part is to determine whether cancer has spread to other parts of the body (metastasized). The TNM system stages metastasis (M) in the following way:

• MX: The presence of distant metastasis cannot be assessed.
• M0: Cancer has not metastasized.
• M1: Cancer has metastasized.

The TNM staging system allows your doctor to recommend the most effective treatment options and discuss your long-term outcome (prognosis) based on the type of tumor, the stage of the cancer, your age, and your overall health.

The stage and TNM class are grouped in the following table.