Basal cell carcinoma develops in the basal cells of the epidermis, the outer layer of the skin. It is the most common type of skin cancer in the United States, but it spreads slowly and is rarely life-threatening. Basal cell carcinoma occurs most often on parts of the body that have been exposed to the sun, such as the face, ears, neck, hands and legs. However, it can be found on any part of the body.