Squamous cell carcinoma, the second most common skin cancer after basal cell carcinoma, afflicts more than 200,000 Americans each year. It arises from the
epidermis and resembles the squamous cells that comprise most of the upper layers
of skin. Squamous cell cancers may occur on all areas of the body including the
mucous membranes, but are most common in areas exposed to the sun.
Although squamous cell carcinomas usually remain confined to the epidermis for
some time, they eventually penetrate the underlying tissues if not treated. In a small percentage of cases, they spread (metastasize) to distant tissues and organs. When
this happens, they can be fatal. Squamous cell carcinomas that metastasize most
often arise on sites of chronic inflammatory skin conditions or on the mucous
membranes or lips.
What Causes It
Chronic exposure to sunlight causes most cases of squamous cell carcinoma. That is why tumors appear most frequently on sun-exposed parts of the body: the face, neck, bald scalp, hands, shoulders, arms, and back. The rim of the ear and the lower lip are especially vulnerable to the development of these cancers.
Who Gets It
Anyone with a substantial history of sun exposure can develop squamous cell carcinoma. But people who have fair skin, light hair, and blue, green, or gray eyes are at highest risk. Those whose occupations require long hours outdoors or who spend extensive leisure time in the sun are in particular jeopardy. Dark-skinned individuals of African descent are far less likely than fair-skinned individuals to develop skin cancer. More than two thirds of the skin cancers that they do develop, however, are squamous cell carcinomas, usually arising on the sites of preexisting inflammatory skin conditions or burn injuries.
Warning Signs of Squamous Cell Carcinoma
- A wart-like growth that crusts and occasionally bleeds.
- A persistent, scaly red patch with irregular borders that sometimes crusts or bleeds.
- An open sore that bleeds and crusts and persists for weeks.
- An elevated growth with a central depression that occasionally bleeds. A growth of this type may rapidly increase in size.