Squamous cell carcinoma, the second most common skin cancer after basal cell carcinoma, afflicts more than 100,000 Americans each year. It arises from the epidermis and resembles the squamous cells that compromise 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 or 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.
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 green, blue 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 they do develop, however, are squamous cell carcinomas, usually arising on the sites of preexisting inflammatory skin conditions or burn injuries.
What to Look For
- A persistent, scaly, red patch with irregular borders that sometimes crusts or bleeds.
- An elevated growth with a central depression that occasionally bleeds. A growth of this type may rapidly increase in size.
- A wart-like growth that crusts and occasionally bleeds.
- An open sore that bleeds and crusts and persists for weeks.
The lesions themselves usually appear as thickened, rough, scaly patches, which can bleed if bumped. They often resemble warts. Occasionally, an open sore will develop with a raised border and a crusted surface over an elevated, pebbly base.
Types of Treatment
After a physician’s examination, a biopsy will be performed to confirm the diagnosis of squamous cell carcinoma. This involves removing a piece of the affected tissue and examining it under a microscope. If tumor cells are present, treatment (usually surgery) is required. Fortunately, there are several effective ways to eradicate squamous cell carcinoma. The choice of treatment is based on the type, size, location, and depth of penetration of the tumor, as well as the patient’s age and general state of health. Surgery can almost always be performed on an outpatient basis in a physician’s office or at a clinic. A local anesthetic is used during most procedures. Pain or discomfort is usually minimal with most techniques, and there is rarely much pain afterwards.
The dermatology specialist uses a scalpel to remove the entire growth and a surrounding border of what happens to be normal skin as a “safety margin.” The incision is then closed with sutures. The removed tissue is sent to the laboratory, where it is examined microscopically to ensure that all the malignant cells have been removed.
CURETTAGE AND ELECTRODESICCATION (ELECTROSURGERY)
The dermatology specialist scrapes the cancerous tissue away from the skin with a sharp, ring-shaped instrument called a curette. Then, an electric needle is used to burn the scraped areas and a margin of normal skin around it. This two-step procedure may be repeated several times, a deeper layer of tissue being scraped and burned each time, until the physician determines that no tumor cells remain.
MOHS MICROGRAPHIC SURGERY
(MISCROSCOPICALLY CONTROLLED SURGERY)
The dermatology specialist removes very thin layers of the malignancy, layer by layer, checking each one thoroughly under a microscope. The excision is repeated until the site or skin is tumor-free. This method saves the greatest amount of healthy tissue and has the highest cure rate. It is frequently used for tumors that are large, recurrent, and located on the face or ears.
Not a Trivial Cancer
When detected in its early stages, squamous cell carcinoma is almost always curable. The larger the tumor has grown, however, the more extensive the treatment will be. Localized tumors that are not treated promptly can result in loss of an eye, ear, or nose, making early detection critical. Although squamous cell carcinoma rarely metastasizes to vital organs, when it does, it is frequently fatal.
Because most treatment options involve cutting the skin, some scarring from removal of the tumor has to be expected. When a small tumor is removed, the result is most often cosmetically quite acceptable. Removal of a larger tumor, however, often requires reconstructive surgery, involving a skin graft or flap to cover the defect.
The Possibility of Recurrence
Anyone who has had one squamous cell tumor has an increased chance of developing another, since the damage the skin has already received from the sun cannot be reversed. Having had a basal cell carcinoma also makes it more likely that a squamous cell carcinoma will develop, because both types of skin cancer are usually caused by excessive sun exposure.
Even though a squamous cell tumor has been carefully removed, another may arise in the same place or nearby. Such recurrences typically occur within the first two years after surgery. Squamous cell carcinomas on the nose, ears, and lips are especially prone to recurrence. Should the cancer recur, the physician may recommend a different type of treatment the second time. Some methods, such as MOHS micrographic surgery, may be more effective than others in such cases. It is important to examine the entire body periodically for warning signs of squamous cell carcinoma. The possibility of recurrence makes it crucial to pay particular attention to any previously treated site. Any changes should be shown immediately to a physician, preferably one who specializes in skin diseases. Even if no suspicious signs are noticed, regularly scheduled follow-up visits are an essential part of post-treatment care.