Squamous Cell Carcinoma

What is squamous cell carcinoma?

Squamous cell carcinoma is cancer that begins in the squamous cells, which are thin, flat cells that look like fish scales under the microscope. The word “squamous” came from the Latin squama, meaning “the scale of a fish or serpent.”Squamous cells are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the passages of the respiratory and digestive tracts. Thus, squamous cell carcinomas can actually arise in any of these tissues.

Squamous cell carcinoma of the skin occurs roughly one-quarter as often as basal cell carcinoma. Light-colored skin and a history of sun exposure are even more important in predisposing to this kind of cancer than to basal cell carcinoma. Men are affected more often than women. Patterns of dress and hairstyle may play a role. Women, whose hair generally covers their ears, develop squamous cell carcinomas far less often in this location than do men.

What are risk factors for developing squamous cell carcinoma?

The single most important factor in producing squamous cell carcinomas is sun exposure. Many such growths can develop from precancerous spots, called actinic or solar keratoses. These lesions appear after years of sun damage on parts of the body like the forehead and cheeks, as well as the backs of the hands. Sun damage takes many years to promote skin cancer. It is therefore common for people who stopped being “sun worshipers” in their twenties to develop precancerous or cancerous spots decades later.

Several rather uncommon factors may predispose to squamous cell carcinoma. These include exposure to arsenic, hydrocarbons, heat, or x-rays. Some squamous cell carcinomas arise in scar tissue. Suppression of the immune system by infection or drugs may also promote such growths.

Can squamous cell carcinoma of the skin spread (metastasize)?

Yes. Unlike basal cell carcinomas, squamous cell carcinomas can metastasize, or spread to other parts of the body. These tumors usually begin as firm, skin-colored or red nodules. Squamous cell cancers that start out within solar keratoses or on sun damaged skin are easier to cure and metastasize less often than those that develop in traumatic or radiation scars. One location particularly prone to metastatic spread is the lower lip. A proper diagnosis in this location is, therefore, especially important.

How is squamous cell carcinoma diagnosed?

As with basal cell carcinoma, make a proper diagnosis doctors usually performs a biopsy. This involves taking a sample by injecting local anesthesia and punching out a small piece of skin using a circular punch blade. Usually the method used referred to as a punch biopsy. The skin that is removed is then examined under a microscope to check for cancer cells.

How is squamous cell carcinoma treated?

Techniques for treating squamous cell carcinoma are similar to those for basal cell carcinoma (for detailed descriptions, see above under treatment of basal cell carcinoma):

Curettage and desiccation: Dermatologists often prefer this method, which consists of scooping out the basal cell carcinoma by using a spoon like instrument called a curette. Desiccation is the additional application of an electric current to control bleeding and kill the remaining cancer cells. The skin heals without stitching. This technique is best suited for small cancers in non-crucial areas such as the trunk and extremities.
Surgical excision: The tumor is cut out and stitched up.
Radiation therapy : Doctors often use radiation treatments for skin cancer occurring in areas that are difficult to treat with surgery. Obtaining a good cosmetic result generally involves many treatment sessions, perhaps 25 to 30.
Cryosurgery: Some doctors trained in this technique achieve good results by freezing basal cell carcinomas. Typically, liquid nitrogen is applied to the growth to freeze and kill the abnormal cells.
Mohs micrographic surgery: Named for its pioneer, Dr. Frederic Mohs, this technique of removing skin cancer is better termed, “microscopically controlled excision.” The surgeon meticulously removes a small piece of the tumor and examines it under the microscope during surgery. This sequence of cutting and microscopic examination is repeated in a painstaking fashion so that the basal cell carcinoma can be mapped and taken out without having to estimate or guess the width and depth of the lesion. This method removes as little of the healthy normal tissue as possible. Cure rate is very high, exceeding 98%. Mohs micrographic surgery is preferred for large basal cell carcinomas, those that recur after previous treatment, or lesions affecting parts of the body where experience shows that recurrence is common after treatment by other methods. Such body parts include the scalp, forehead, ears, and the corners of the nose. In cases where large amounts of tissue need to be removed, the Mohs surgeon sometimes works with a plastic (reconstructive) surgeon to achieve the best possible post-surgical appearance.

The possibility of metastasis makes it especially important to diagnose squamous cell carcinomas early and treat them adequately.

How is squamous cell carcinoma prevented?

Even more so than is the case with basal cell carcinoma, the key principles of prevention are minimizing sun exposure and getting regular checkups.

Common sense preventive techniques are the same as for basal cell carcinoma and include:
Limiting recreational sun exposure
Avoiding unprotected exposure to the sun during peak radiation times (the hours surrounding noon)
Wearing broad-brimmed hats and tightly-woven protective clothing while outdoors in the sun
Regularly using a waterproof or water resistant sunscreen with UVA protection and SPF number of 30 or higher
Undergoing regular checkups and bringing any suspicious-looking or changing lesions to the attention of a doctor