Stages of Skin Cancer

After nonmelanoma skin cancer has been diagnosed, tests are done to find out if cancer cells have spread within the skin or to other parts of the body.

The process used to find out if cancer has spread within the skin or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. A biopsy is often the only test needed to determine the stage of nonmelanoma skin cancer. Lymph nodes may be examined in cases of squamous cell carcinoma to see if cancer has spread to them.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

• Through tissue. Cancer invades the surrounding normal tissue.
• Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
• Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

Staging of nonmelanoma skin cancer depends on many factors, including whether the tumor has certain "high-risk" features.

Millimeters (mm). A sharp pencil point is about 1 mm, a new crayon point is about 2 mm, and a new pencil eraser is about 5 mm.

The following are high-risk features for nonmelanoma skin cancer:

• The tumor is thicker than 2 millimeters.
• The tumor is described as Clark level IV (has spread into the lower layer of the dermis) or Clark level V (has spread into the layer of fat below the skin).
• The tumor has grown and spread along nerve pathways.
• The tumor began on an ear or on a lip that has hair on it.
• The tumor has cells that look very different from normal cells under a microscope.

The following stages are used for nonmelanoma skin cancer:

Stage 0 (Carcinoma in Situ)

Stage 0 nonmelanoma skin carcinoma in situ. Abnormal cells are shown in the epidermis (outer layer of the skin).

In stage 0, abnormalcells are found in the squamous cell or basal cell layer of the epidermis (topmost layer of the skin). These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.

Pea, peanut, walnut, and lime show tumor sizes.

Stage I

Stage I nonmelanoma skin cancer. The tumor is no more than 2 centimeters.

In stage I, cancer has formed. The tumor is not larger than 2 centimeters at its widest point and may have one high-risk feature.

Stage II

In stage II, the tumor is either:

• larger than 2 centimeters at its widest point; or
• any size and has two or more high-risk features.

Stage III

In stage III:

• The tumor has spread to the jaw, eye socket, or side of the skull. Cancer may have spread to one lymph node on the same side of the body as the tumor. The lymph node is not larger than 3 centimeters.

or

• Cancer has spread to one lymph node on the same side of the body as the tumor. The lymph node is not larger than 3 centimeters and one of the following is true:
  • the tumor is not larger than 2 centimeters at its widest point and may have one high-risk feature; or
  • the tumor is larger than 2 centimeters at its widest point; or
  • the tumor is any size and has two or more high-risk features.

Stage IV

In stage IV, one of the following is true:

• The tumor is any size and may have spread to the jaw, eye socket, or side of the skull. Cancer has spread to one lymph node on the same side of the body as the tumor and the affected node is larger than 3 centimeters but not larger than 6 centimeters, or cancer has spread to more than one lymph node on one or both sides of the body and the affected nodes are not larger than 6 centimeters; or
• The tumor is any size and may have spread to the jaw, eye socket, skull, spine, or ribs. Cancer has spread to one lymph node that is larger than 6 centimeters; or
• The tumor is any size and has spread to the base of the skull, spine, or ribs. Cancer may have spread to the lymph nodes; or
• Cancer has spread to distant parts of the body.

Treatment choices are based on the type of nonmelanoma skin cancer or precancerous skin condition diagnosed:

Basal cell carcinoma

Basal cell carcinoma is the most common type of skin cancer. It usually occurs on areas of the skin that have been in the sun, most often the nose. Often this cancer appears as a small raised bump that has a smooth, pearly appearance. Another type looks like a scar and is flat and firm to the touch. Basal cell carcinoma may spread to tissues around the cancer, but it usually does not spread to other parts of the body.

Squamous cell carcinoma

Squamous cell carcinoma occurs on areas of the skin that have been in the sun, such as the ears, lower lip, and the back of the hands. Squamous cell carcinoma may also appear on areas of the skin that have been burned or exposed to chemicals or radiation. Often this cancer appears as a firm red bump. Sometimes the tumor may feel scaly or bleed or develop a crust. Squamous cell tumors may spread to nearby lymph nodes.

Actinic keratosis

Actinic keratosis is a skin condition that is not cancer, but sometimes changes into squamous cell carcinoma. It usually occurs in areas that have been exposed to the sun, such as the face, the back of the hands, and the lower lip. It appears as rough, red, pink, or brown, raised, scaly patches on the skin, or cracking or peeling of the lower lip that is not helped by lip balm or petroleum jelly.