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Squamous cell carcinoma arises from keratinocytes, skin cells found in the upper layers of the skin (epidermis). These cancers often present as crusty or scaly skin lesions that have a red base and may be tender to the touch. Although squamous cell carcinoma can develop anywhere, including in the inside of the mouth and on genitalia, it frequently appears on sun-exposed areas such as the scalp, face, ears and back of hands - areas where we forget to apply sunscreen.
Symptoms of squamous cell carcinoma
Squamous cell carcinomas typically appear as a persistent thick, rough, scaly patch that can bleed if bumped. They often look like warts and sometimes appear as open sores with a raised border and a crusted surface over an elevated pebbly base.
Who it affects
People who have fair skin, light hair, and blue, green, or gray eyes are at highest risk of developing the disease. But anyone with a history of substantial sun exposure is at increased risk. Those whose occupations require long hours outdoors or who spend extensive leisure time in the sun are in particular jeopardy. Anyone who has had a basal cell carcinoma is also more likely to develop a squamous cell carcinoma.
Squamous cell carcinomas are at least twice as frequent in men as in women. They rarely appear before age 50 and are most often seen in individuals in their 70s.
The majority of skin cancers in people with darker skin tones are squamous cell carcinomas, usually arising on the sites of preexisting inflammatory skin conditions or burn injuries. Though naturally dark-skinned people are less likely than fair-skinned people to get skin cancer, it is still essential for them to practice sun protection.
Causes of squamous cell carcinoma
Chronic exposure to sunlight causes most cases of squamous cell carcinoma. Exposure to ultraviolet light from tanning beds can increase the risk of squamous cell carcinoma. Skin injuries are another important source. The cancer can arise in burns, scars, ulcers, long-standing sores and sites previously exposed to X-rays or certain chemicals (such as arsenic and petroleum by-products). Chronic infections and skin inflammation can also give rise to squamous cell carcinoma. Occasionally, squamous cell carcinomas appear spontaneously on what appears to be normal, healthy skin.
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 and spread to other parts of the body. If you see new lesions or any skin lesions that are suspicious, you should make an appointment at the Dermatological Center for Skin Health where we will perform a complete skin examination, including a biopsy if a lesion is suspicious. If squamous cell carcinoma is diagnosed, 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 health. Treatment can almost always be performed on an outpatient basis. A local anesthetic is used during most surgical procedures. Pain or discomfort is usually minimal with most techniques, and there is rarely much pain afterwards.
Mohs Micrographic Surgery
Using a scalpel or curette (a sharp, ring-shaped instrument), we remove the visible tumor with a very thin layer of tissue around it. This layer is immediately checked under a microscope. If tumor is still present in the depths or peripheries of this surrounding tissue, the procedure is repeated until the last layer viewed under the microscope is tumor-free. Mohs saves the greatest amount of healthy tissue, appears to reduce the rate of local recurrence, and has the highest overall cure rate — up to 99% – of any treatment for squamous cell carcinoma. It is frequently used on tumors that have recurred, are poorly demarcated, or are in hard-to-treat, critical areas around the eyes, nose, lips, and ears, as well as the neck, hands and feet. We don’t currently offer this treatment at the Dermatological Center for Skin Health but can refer you to others who do if necessary.
We use 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 stitches. The excised tissue is then sent to our lab for microscopic examination to verify that all cancerous cells have been removed. 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 (Electrosurgery)
The growth is scraped off with a curette, 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 considered as effective for more invasive, aggressive squamous cell carcinomas or those in high-risk or difficult sites, such as the eyelids, genitalia, lips and ears.
With cryosurgery, we destroy 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 can have a lower overall cure rate than the surgical methods.
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. Saint John’s Health Center has an advanced radiology department to handle your radiation therapy.
Photodynamic Therapy (PDT)
PDT can be especially useful for growths on the face and scalp. A photosensitizing agent, which is absorbed by abnormal cells, is applied to the growths at the physician's office. The next day, the patient returns, and those medicated areas are activated by a strong light. The treatment selectively destroys squamous cell carcinomas while causing minimal damage to surrounding normal tissue. We don’t currently offer this treatment at the Dermatological Center for Skin Health but can refer you to physicians who do if necessary.
5-fluorouracil (5-FU) and imiquimod, both FDA-approved for treatment of actinic keratoses and superficial basal cell carcinomas, are also being tested for the treatment of some superficial squamous cell carcinomas. Neither treat has been approved for this indication yet.