Skin Cancer

skin cancer, disease characterized by the uncontrolled growth of cells in the skin. Skin cancers are of two distinct types: nonmelanoma and melanoma. Together they account for approximately half of all reported cancers. Melanomas are cancers of pigmented cells and are far more dangerous than nonmelanomas, which are the most common cancers in the United States. This article discusses nonmelanoma skin cancers.

Nonmelanomas are cancers of surface tissues (carcinomas). There are two forms of nonmelanoma, both of which can usually be cured with minor surgery. Squamous cell carcinomas develop from a layer of flat cells close to the skin’s surface and account for about one-fourth of nonmelanoma cases. Basal cell carcinomas account for roughly three-fourths of cases, and as many as 50 percent of patients with this form of the disease develop another skin cancer within five years of initial diagnosis. Basal cell carcinoma begins in a layer of cells underlying the squamous cells. The squamous and basal cell layers are both located in the epidermis.