The metastatic tumor is the same type of cancer as the primary tumor. For example, if skin cancer spreads to the lung, the cancer cells in the lung are actually skin cancer cells. The disease is metastatic skin cancer, not lung cancer.
Staging of nonmelanoma skin cancer depends on whether the tumor has certain "high-risk" features and if the tumor is on the eyelid.
Staging for nonmelanoma skin cancer that is on the eyelid is different from staging for nonmelanoma skin cancer that affects other parts of the body.
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 that is not on the eyelid:
- 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 that is not on the eyelid:
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, abnormal cells 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 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 nonmelanoma skin cancer. The tumor is more than 2 centimeters wide.