Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Skin Cancer ?
    ### Response:
    Key Points
                    - Skin cancer is a disease in which malignant (cancer) cells form in the tissues of the skin.    - Nonmelanoma skin cancer is the most common cancer in the United States.    - Being exposed to ultraviolet radiation may increase the risk of skin cancer.
    