Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) is the second most common type of skin cancer. It occurs more often in men than in women at a 2:1 ratio. Squamous cell carcinoma of the skin is an invasive tumor arising from keratinizing epidermal cells; it has the potential for metastasis. Squamous cell carcinoma occurs most commonly in fair-skinned white men over age 60. Outdoor employment and residence in a sunny, warm climate (southern United States and Australia, for example) greatly increase the risk for squamous cell carcinoma.

Lesions on sun-damaged skin tend to be less invasive with less tendency to metastasize than lesions on unexposed skin. Notable exceptions are squamous cell lesions on the lower lip and the ears; almost invariably, these are markedly invasive metastatic lesions with a poor prognosis.

Causes

The majority of squamous cell carcinomas are caused by chronic sun exposure. Squamous cell carcinomas may also occur where skin has suffered certain kinds of injury such as burns, scars, non-healing ulcers, exposure to certain chemicals (such as arsenic and petroleum by-products), and radiation. In addition, chronic skin inflammation or medical conditions that suppress the immune system over an extended period of time (such as an organ transplant) may encourage the development of squamous cell carcinoma.

Signs and Symptoms

Squamous cell carcinoma commonly develops on the skin of the face, the ears, the dorsa of the hands and fore­arms, and other sun-damaged areas. Lesions on sun-damaged skin tend to be less invasive and less likely to metastasize than lesions on unexposed skin.

Notable exceptions to this tendency are squamous cell lesions on the lower lip and the ears. These are almost invariably markedly invasive metastastic lesions with a generally poor prognosis.

Transformation from a premalignant lesion to squamous cell carcinoma may begin with induration and inflammation of the preexisting lesion. When squamous cell carcinoma arises from normal skin, the nodule grows slowly on a firm, indurated base.

If untreated, this nodule eventually ulcerates and invades underlying tissues. Metastasis can occur to the regional lymph nodes, producing characteristic systemic symptoms of pain, malaise, fatigue, weakness, and anorexia

Diagnostic tests 

An excisional biopsy provides a definitive diagnosis of squamous cell carcinoma. Appropriate laboratory tests depend on systemic symptoms.

Treatment

The treatment varies with the tumor's size, depth, location and how much it has spread ( metastasis ).

Surgical removal of the tumor, which may include removal of the skin around the tumor (wide excision), is often recommended. Microscopic shaving (Mohs' surgery) may remove small tumors. Skin grafting may be needed if wide areas of skin are removed.

The tumor may be reduced in size by radiation treatments.

Chemotherapy can be used if surgery and radiation fail, but it is usually minimally effective.

Prevention

• Use sunscreen of at least SPF15 and wear a broad brimmed hat
• Some who have had a squamous cell carcinoma need to come back every three months for two years for a skin exam and then every six months for life. Most recurrences are in the first two years.
• Eat a healthy, low fat diet.
• Use high-quality sunscreens, preferably with SPF (sun protection factor) ratings of at least 15. Apply the sunscreen at least a half hour before exposure and re-apply frequently.