cancer of the outer surface of the body. The most common cancer in the U.S. There are many types of skin cancer. Ultraviolet light from sunlight is the main cause of skin cancer. Unexplained changes in the appearance of the skin, lasting longer than 2 weeks, should be evaluated by a doctor. The cure rate for skin cancer could be 100% if all skin cancers were brought to a doctors attention before they had a chance to spread.