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.