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Skin cancer is the most common type of cancer and usually develops in sun-exposed areas of skin. The incidence is highest among outdoor workers, sportsmen, and sunbathers and is inversely related to the amount of melanin skin pigmentation; fair-skinned people are most susceptible. Skin cancers may also develop years after therapeutic x-ray or exposure to carcinogens (eg, arsenic ingestion).
Over one million new cases of skin cancer are diagnosed in the US yearly. (See also the US Preventive Services Task Force summary of recommendations for screening and counseling for skin cancer.) About 80% are basal cell carcinoma, 16% are squamous cell carcinoma, and 4% are melanoma. Paget's disease of the nipple or extramammary Paget's (usually near the anus), Kaposi's sarcoma, tumors of adnexa, and cutaneous T-cell lymphoma (mycosis fungoides—see Lymphomas: Mycosis Fungoides) make up the remaining, less common forms of skin cancer.
Initially, skin cancers are often asymptomatic. The most frequent presentation is a papule or blind pimple that does not go away. Any lesion that appears to be enlarging should be biopsied—whether tenderness, mild inflammation, crusting, or occasional bleeding is present or not. If treated early, most skin cancers are curable.
Screening
Routine screening for skin cancer is by patient self-examination, physician examination, or both.
Prevention
Because many skin cancers seem to be related to ultraviolet (UV) exposure, a number of measures are recommended to limit exposure.
Current evidence is inadequate to determine whether these measures reduce incidence or mortality of melanoma; in nonmelanoma skin cancers (basal cell and squamous cell carcinoma), sun protection does decrease the incidence of new cancers.
Last full review/revision October 2008 by Gregory L. Wells, MD
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