Skin Cancer

Skin cancer is the abnormal growth of skin cells. It most often develops on skin that is exposed to the sun, it can also occur on areas of your skin not ordinarily exposed to sunlight.

The skin is the largest organ in the body and it protects against heat, sunlight, injury, and infection. Skin also helps control body temperature and stores water and fat.

Skin cancer is the most common of all cancers, and there are three major types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma. Rare types of skin cancer include Merkel cell carcinoma, skin lymphoma, and Kaposi sarcoma. Basal cell cancer and squamous cell cancer usually form on the head, face, neck, hands, and arms. Melanoma is more dangerous than carcinomas, but it is less common. Approximately 3.5 million cases of basal and squamous cell skin cancer are diagnosed in the United States each year. Melanoma, a more dangerous type of skin cancer, accounts for more than 73,000 cases of skin cancer per year.

You can reduce your risk of skin cancer by limiting or avoiding exposure to ultraviolet (UV) radiation. Checking your skin for suspicious changes can help detect skin cancer at its earliest stages. Early detection of skin cancer gives you the greatest chance for successful skin cancer treatment. If not treated, some types of skin cancer cells can spread to other tissues and organs. Treatments include surgery, radiation therapy, chemotherapy, photodynamic therapy (PDT), and biologic therapy.

Skin cancer occurs when errors (mutations) occur in the DNA of skin cells. The mutations cause the cells to grow out of control and form a mass of cancer cells.

Skin cancer begins in your skin's top layer — the epidermis. The epidermis is a thin layer that provides a protective cover of skin cells that your body continually sheds. The epidermis contains three main types of cells:

• squamous cells, which lie just below the outer surface and function as the skin's inner lining
• basal cells, which sit beneath the squamous cells and produce new skin cells
• melanocytes, which are located in the lower part of your epidermis and produce melanin, the pigment that gives skin its normal color

Much of the damage to DNA in skin cells results from ultraviolet (UV) radiation found in sunlight and in the lights used in tanning beds. However, sun exposure does not explain skin cancers that develop on skin not ordinarily exposed to sunlight. This indicates that other factors may contribute to your risk of skin cancer, such as being exposed to toxic substances or having a condition that weakens your immune system.

Risk factors for skin cancer include:

• too much exposure to ultraviolet (UV) radiation (from sunlight or tanning beds and lamps)
• fair or pale skin (easily sunburned, doesn’t tan much or at all, natural red or blond hair)
• exposure to large amounts of coal tar, paraffin, arsenic compounds, or certain types of oil
• family history of skin cancers
• multiple or unusual moles
• severe sunburns in the past
• weakened immune system
• older age (although melanomas can also occur in younger people)

See a doctor or dermatologist for a new or changing mole or spot, a sore that will not heal, or any growth with an irregular shape, border, or color. Early detection makes skin cancer highly treatable.