They include a personal or family history of melanoma and the presence of atypical, large, or numerous (more than 50) moles. Heavy exposure to ultraviolet (UV) radiation, from sunlight or the use of indoor tanning, is a risk factor for all types of skin cancer, and indoor tanning devices are classified as carcinogenic by the International Agency for Research on Cancer. Risk is also increased for people who are sun-sensitive (e.g., sunburn easily or have natural blond or red hair color) and those who have a history of excessive sun exposure (including sunburns) or skin cancer. People with a weakened immune system are also at increased risk for skin cancer.