Studies have found the following risk factors for skin cancer:

• Ultraviolet (UV) radiation: UV radiation comes from the sun, sunlamps, tanning beds, or tanning booths. A person's risk of skin cancer is related to lifetime exposure to UV radiation. Most skin cancer appears after age 50, but the sun damages the skin from an early age.

  UV radiation affects everyone. But people who have fair skin that freckles or burns easily are at greater risk. These people often also have red or blond hair and light-colored eyes. But even people who tan can get skin cancer.

  People who live in areas that get high levels of UV radiation have a higher risk of skin cancer. In the United States, areas in the south (such as Texas and Florida) get more UV radiation than areas in the north (such as Minnesota). Also, people who live in the mountains get high levels of UV radiation.

  UV radiation is present even in cold weather or on a cloudy day.

• Scars or burns on the skin
• Infection with certain human papillomaviruses
• Exposure to arsenic at work
• Chronic skin inflammation or skin ulcers
• Diseases that make the skin sensitive to the sun, such as xeroderma pigmentosum, albinism, and basal cell nevus syndrome
• Radiation therapy
• Medical conditions or drugs that suppress the immune system
• Personal history of one or more skin cancers
• Family history of skin cancer
• Actinic keratosis: Actinic keratosis is a type of flat, scaly growth on the skin. It is most often found on areas exposed to the sun, especially the face and the backs of the hands. The growths may appear as rough red or brown patches on the skin. They may also appear as cracking or peeling of the lower lip that does not heal. Without treatment, a small number of these scaly growths may turn into squamous cell cancer.
• Bowen's disease: Bowen's disease is a type of scaly or thickened patch on the skin. It may turn into squamous cell skin cancer.