Squamous Cell Carcinoma
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.
Squamous cell carcinomas may also occur where skin has suffered certain kinds of injury: burns, scars, long-standing sores, sites previously exposed to X-rays or certain chemicals (such as arsenic and petroleum by-products). In addition, chronic skin inflammation or medical conditions that suppress the immune system over an extended period of time may encourage development of squamous cell carcinoma.
Occasionally, squamous cell carcinoma arises spontaneously on what appears to be normal, healthy, undamaged skin. Some researchers believe that a tendency to develop this cancer may be inherited.
Can squamous cell carcinoma be prevented?
Ultraviolet light avoidance is the primary form of prevention and is important at all ages. Outdoor activity should be avoided between late morning and early afternoon, tanning parlors should be shunned, and wide brimmed hats should be worn along with other protective clothing. Sunscreens with SPF 15 or higher and UVA block should be applied regularly even for a brief exposure to sunlight.
How do dermatologists treat squamous cell carcinoma?
Dermatologists use a variety of different surgical treatment options depending on location of the tumor, size of the tumor, microscopic characteristics of the tumor, health of the patient, and other factors. Most treatment options are relatively minor office-based procedures that require only local anesthesia. Surgical excision to remove the entire cancer is the most commonly used treatment option. "Mohs" micrographic surgery, a more involved method requiring specialized training by dermatologic surgeons, can be used to remove the whole tumor while sparing as much normal skin as possible. Other dermatologic surgery treatments include laser surgery, cryosurgery with liquid nitrogen (the "frozen" method), radiation therapy, and electrodesiccation and curettage (called "ED&C"), which involves alternately scraping or burning the tumor in combination with low levels of electricity.
(above information, except photographs, adapted from Skin Cancer Foundation)
Dr. Crutchfield recommends the following helpful Patient information:
Dr. Crutchfield's United Hospital Sun Protection Article
American Academy of Dermatology: Squamous Cell Skin Cancer
American Academy of Dermatology: Skin Cancer