Squamous Cell Carcinoma

Squamous cell carcinoma is the second most common skin cancer and is diagnosed in more than 200,000 Americans each year. Squamous cell carcinoma arises from cells in the epidermis (outermost layer of skin), and although it most often occurs in sun-exposed skin, it may occur anywhere on the body. Although squamous cell carcinomas usually remain confined to the skin for some time, they may eventually penetrate the underlying tissues if not treated. In a small percentage of cases, they spread (metastasize) to local lymph nodes, distant tissues or organs. When this happens, they can be fatal. Squamous cell carcinomas that metastasize most often are large in size and/or ulcerated and often arise on chronic wounds, mucous membranes, lips, or ears.

Chronic exposure to sunlight (ultraviolet radiation) is the most common cause of squamous cell carcinoma, and tumors most frequently appear on the 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. Squamous cell carcinomas may also occur where skin has suffered certain kinds of injury: burns, scars, long-standing sores, sites previously treated with radiation or chronically exposed to chemicals such as arsenic. Development of squamous cell carcinoma is encouraged by medical conditions that suppress the immune system such as organ transplant medications or HIV.

Anyone with a history of frequent sun exposure can develop SCC, but people who have fair skin, light hair, or light eyes are at highest risk. Those whose occupations require long hours in the outdoors or who spend extensive leisure time in the sun are in particular jeopardy. Dark-skinned individuals are far less likely than fair-skinned to develop skin cancer.

Certain precursor conditions, some of which result from extensive sun damage, are worth noting. They are sometimes associated with the later development of squamous cell carcinoma. They include: Actinic, or solar keratosis. Actinic keratoses are rough, scaly, slightly raised growths that range in color from brown to red and may be up to one inch in diameter. They appear most often in older people. Actinic cheilitis. A type of actinic keratosis occurring on the lips, it causes them to become dry, cracked, scaly, and pale or white. It mainly affects the lower lip, which typically receives more sun exposure than the upper lip.

The development of a new growth or open sore that does not heal should prompt skin examination by a dermatologist. Early detection of squamous cell carcinoma simplifies treatment and reconstruction and decreases the chance for metastasis. We also recommend regular self-skin examination — as often as once a month if you are at high risk. Be sure to include the scalp, backs of ears, neck, and other hard-to-see areas. Your physician will suggest the correct time frame for follow-up visits, depending on your specific risk factors, such as skin type and history of sun exposure.