Squamous cell carcinoma (SCC) is an uncontrolled growth of abnormal cells arising in the squamous cells, which compose most of the skin’s upper layers (the epidermis). SCCs often look like scaly red patches, open sores, scaly elevated growths with a central depression, or warts; they may crust or bleed. They can become disfiguring and sometimes deadly if allowed to grow. More than 1 million cases of squamous cell carcinoma are diagnosed each year in the U.S., and (depending on different estimates) as many as 8,800 people die from the disease. Incidence of the disease has increased up to 200 percent in the past three decades in the U.S.
SCC is mainly caused by cumulative ultraviolet (UV) exposure over the course of a lifetime; daily year-round exposure to the sun’s UV light, intense exposure in the summer months, and the UV produced by tanning beds all add to the damage that can lead to SCC.
SCCs may occur on all areas of the body including the mucous membranes and genitals, but are most common in areas frequently exposed to the sun, such as the rim of the ear, lower lip, face, balding scalp, neck, hands, arms and legs. Often the skin in these areas reveals telltale signs of sun damage, including wrinkles, pigment changes, freckles, “age spots,” loss of elasticity, and broken blood vessels. Risk factors for Squamous Cell Carcinoma include fair skin, excessive sun exposure, history of sunburns, use of tanning beds, history of previous skin cancer, or a weakened immune system/immunosuppression.
Treatment of Squamous Cell Carcinoma
Squamous cell carcinomas detected at an early stage and removed promptly are almost always curable and cause minimal damage. However, left untreated, they eventually penetrate the underlying tissues and can become disfiguring. A small percentage even metastasize to local lymph nodes, distant tissues, and organs and can become fatal. Therefore, any suspicious growth should be seen by a dermatologist without delay. A tissue sample (biopsy) will be examined under a microscope to arrive at a diagnosis. If tumor cells are present, treatment is required. Fortunately, there are several effective ways to eradicate squamous cell carcinoma. The choice of treatment is based on the tumor’s type, size, location, and depth of penetration, as well as the patient’s age and general health. Treatment options include excision, electrodessication and curetage, Mohs surgery, Cryosurgery, anti-cancer medications and radiation.
Using a scalpel, a physician trained in Mohs surgery removes the visible tumor with a very thin layer of tissue around it. While the patient waits, this layer is sectioned, frozen, stained and mapped in detail, then checked under a microscope thoroughly. If cancer is still present in the depths or peripheries of this excised surrounding tissue, the procedure is repeated on the corresponding area of the body still containing tumor cells until the last layer viewed under the microscope is cancer-free. Mohs surgery spares the greatest amount of healthy tissue, reduces the rate of local recurrence, and has the highest overall cure rate (94-99 percent) of any treatment for SCC. It is often used on tumors that have recurred, are poorly demarcated, or are in hard-to-treat, critical areas around the eyes, nose, lips, ears, neck, hands and feet. After tumor removal, the wound may be allowed to heal naturally or may be reconstructed immediately; the cosmetic outcome is usually excellent.
The physician uses a scalpel to remove the entire growth, along with a surrounding border of apparently normal skin as a safety margin. The wound around the surgical site is then closed with sutures (stitches). The excised tissue specimen is then sent to the laboratory for microscopic examination to verify that all cancerous cells have been removed. A repeat excision may be necessary on a subsequent occasion if evidence of skin cancer is found in the specimen. The accepted cure rate for primary tumors with this technique is about 92 percent. This rate drops to 77 percent for recurrent squamous cell carcinomas.
Curettage and Electrodesiccation
The growth is scraped off with a curette (an instrument with a sharp, ring-shaped tip), and burning heat produced by an electrocautery needle destroys residual tumor and controls bleeding. This procedure is typically repeated a few times, a deeper layer of tissue being scraped and burned each time to help ensure that no tumor cells remain. It can produce cure rates approaching those of surgical excision for superficially invasive squamous cell carcinomas without high-risk characteristics. However, it is not recommended for any invasive or aggressive SCCs, those in high-risk or difficult sites, such as the eyelids, genitalia, lips and ears, or other sites that would be left with cosmetically undesirable results, since the procedure leaves a sizable, hypopigmented scar.
The physician destroys the tumor tissue by freezing it with liquid nitrogen, using a cotton-tipped applicator or spray device. There is no cutting or bleeding, and no anesthesia is required. The procedure may be repeated several times at the same session to help ensure destruction of all malignant cells. The growth becomes crusted and scabbed, and usually falls off within weeks. Redness, swelling, blistering and crusting can occur following treatment, and in dark-skinned patients, some pigment may be lost. Inexpensive and easy to administer, cryosurgery may be the treatment of choice for patients with bleeding disorders or intolerance to anesthesia. However, it has a lower overall cure rate than the surgical methods. Depending on the physician’s expertise, the 5-year cure rate can be quite high with selected, generally superficial squamous cell carcinoma; but cryosurgery is not often used today for invasive SCC because deeper portions of the tumor may be missed and because scar tissue at the cryotherapy site might obscure a recurrence.
X-ray beams are directed at the tumor, with no need for cutting or anesthesia. Destruction of the tumor usually requires a series of treatments, administered several times a week for one to four weeks, or sometimes daily for one month. Cure rates range widely, from about 85 to 95 percent, since the technique does not provide precise control in identifying and removing residual cancer cells at the margins of the tumor. The technique can involve long-term cosmetic problems and radiation risks, as well as multiple visits. For these reasons, though this therapy limits damage to adjacent tissue, it is mainly used for tumors that are hard to treat surgically, as well as patients for whom surgery is not advised, such as the elderly or those in poor health.
Photodynamic Therapy (PDT)
PDT can be especially useful for growths on the face and scalp. A chemical agent that reacts to light, such as topical 5-aminolevulinic acid (5-ALA) or methyl aminolevulinate (MAL), is applied to the affected skin at the dermatologist’s office; it is taken up by the abnormal cells. Hours later, those medicated areas are activated by a blue light. The treatment selectively premalignant and some malignant cells while causing minimal damage to surrounding normal tissue. After treatment, patients become locally photosensitive for 48 hours where the light-sensitizing agent was applied, and must avoid both outdoor and indoor light and be careful to use sun protection.