Skin cancer is the most common form of cancer. Over 3.5 million new cases of skin cancer are diagnosed in over 2 million people in the United States each year. The three main types of skin cancer—basal cell carcinoma, squamous cell carcinoma, and melanoma—are caused, at least in part, by long-term sun exposure. Lymphoma can also develop in the skin (see Sidebar: Overview of Lymphoma). Skin cancer is most common among people who work or play sports outside and sunbathers. Fair-skinned people are particularly susceptible to developing most forms of skin cancer because they produce less melanin. Melanin, the protective pigment in the outer layer of skin (epidermis), helps protect the skin from ultraviolet (UV) light. However, skin cancer also can develop in dark-skinned people and in people whose skin has not had significant sun exposure. Skin cancers may also develop years after x-ray therapy or exposure to substances that cause cancer (for example, ingestion of arsenic).
Most skin cancers are curable, especially when treated at an early stage. At first, skin cancers do not cause any symptoms. Therefore, any unusual skin growth that enlarges or persists for more than a few weeks is best examined by a doctor.
Doctors treat most skin cancers by removing them surgically. Usually, the scar that is left after surgery is small. Larger or more invasive cancer may require removal of a significant amount of skin, which may have to be replaced with a skin graft or a skin flap (see see Skin). With a graft, a piece of skin is removed from another area of the person's body, typically where the skin is loose. The piece of skin is sewn onto the area where the cancer was removed. With a flap, doctors transfer skin from an adjacent area to replace the area where the cancer was removed. With a flap, but not with a graft, the transferred skin is not cut completely free, so it still has its own blood supply. Also, a flap is usually thicker than a graft.
Although people should notify their doctor of any unusual or changed skin marks, doctors do not know whether routine yearly skin examinations to screen for skin cancer would reduce the number of deaths from skin cancer.
Because many skin cancers seem to be related to UV exposure, doctors recommend a number of measures to limit UV exposure.
However, current evidence is inadequate to determine whether these measures reduce the chances of people developing or dying from melanoma. In people with a history of nonmelanoma skin cancers (that is, basal cell carcinoma or squamous cell carcinoma), sun protection does decrease the risk of developing new cancers.
Last full review/revision July 2013 by Gregory L. Wells, MD