What Is Skin Cancer?Like other types of cancer, skin cancer often starts with DNA damage. DNA damage can be caused by many different carcinogens, but UV radiation from the sun causes most of the damage that eventually leads to skin cancer. Damage that occurs due to occasional sun exposure is usually repaired by built-in DNA repair mechanisms in your body. But, long-term sun exposure can lead to DNA damage that is not repaired. If this damage occurs in genes that are responsible for controlling the division of skin cells, these cells may begin to divide uncontrollably, which can result in skin cancer. Skin cancer most commonly occurs within the epidermis, because it sustains the most damage from the sun. Skin cancer typically affects three different types of cells in the epidermis, known squamous cells, basal cells, and melanocytes. Squamous cells are cells that have flattened as they progress from the basal cell layer toward the skin?s surface, where they are shed. Basal cells are the bottommost epidermal cells that lie along the junction between the epidermis and dermis. As these cells divide, they produce new cells that eventually become squamous cells, which constantly replace the dead skin cells that are shed at the skin?s surface. Melanocytes are a special type of cell located in the basal layer of the epidermis. These cells are responsible for producing melanin, or pigment, which gives your skin and hair its color.What Is Skin Cancer?Like other types of cancer, skin cancer often starts with DNA damage. DNA damage can be caused by many different carcinogens, but UV radiation from the sun causes most of the damage that eventually leads to skin cancer. Damage that occurs due to occasional sun exposure is usually repaired by built-in DNA repair mechanisms in your body. But, long-term sun exposure can lead to DNA damage that is not repaired. If this damage occurs in genes that are responsible for controlling the division of skin cells, these cells may begin to divide uncontrollably, which can result in skin cancer. Skin cancer most commonly occurs within the epidermis, because it sustains the most damage from the sun. Skin cancer typically affects three different types of cells in the epidermis, known squamous cells, basal cells, and melanocytes. Squamous cells are cells that have flattened as they progress from the basal cell layer toward the skin?s surface, where they are shed. Basal cells are the bottommost epidermal cells that lie along the junction between the epidermis and dermis. As these cells divide, they produce new cells that eventually become squamous cells, which constantly replace the dead skin cells that are shed at the skin?s surface. Melanocytes are a special type of cell located in the basal layer of the epidermis. These cells are responsible for producing melanin, or pigment, which gives your skin and hair its color.