Skin cancer is the most common form of cancer in the United States. 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 see Lymphomas: Overview of Lymphoma). 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 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. Most skin cancers are curable, especially when treated at an early stage. Therefore, any unusual skin growth that 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 (see Transplantation: Transplantation of Other Organs).

Screening: 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.

Prevention: Because many skin cancers seem to be related to UV exposure, doctors recommend a number of measures to limit UV exposure.

Did You Know... Most skin cancers are caused, at least in part, by spending a lot of time in the sun.

• Avoid the sun (for example, seek shade, minimize outdoor activities between 10 am and 3 pm, when the sun's rays are strongest, and avoid sunbathing and the use of tanning beds)
• Wear protective clothing (eg, long-sleeved shirt, pants, broad-brimmed hat)
• Use sunscreen (at least SPF 30 with UVA protection, used as directed), but sunscreen should not be used in order to prolong sun exposure.

However, current evidence is inadequate to determine whether these measures reduce the chances of people getting 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 October 2008 by Gregory L. Wells, MD