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Squamous Cell Carcinoma


Vinod E. Nambudiri

, MD, MBA, EdM, Harvard Medical School

Reviewed/Revised Jan 2024
Topic Resources

Squamous cell carcinoma is cancer that begins in the squamous cells of the skin.

  • Thick, scaly growths appear on the skin and do not heal.

  • To diagnose the cancer, doctors do a biopsy.

  • Treatment with surgery, chemotherapy applied to the skin, and sometimes radiation therapy can usually cure the cancer unless it has spread.

  • If the cancer has spread, people may be given medications called PD-1 inhibitors.

  • If the cancer spreads to other parts of the body, it can be fatal.

Squamous cells (keratinocytes) are the main structural cells of the epidermis (the outer layer of skin). Squamous cell carcinoma is cancer of these cells. Each year in the United States, 1.8 million people are diagnosed with squamous cell carcinoma.

People who have had more sun exposure to their skin have a higher risk of developing squamous cell skin cancer. People who have light skin are much more susceptible to squamous cell carcinoma than people who have dark skin.

Squamous cell carcinoma may develop on normal skin but is more likely to develop in damaged skin. Such damage includes

In the mouth, precancerous skin growths appear as white or red spots (leukoplakia Precancerous changes in the mouth Precancerous changes in the mouth or erythroplakia Precancerous changes in the mouth Precancerous changes in the mouth ).

Symptoms of Squamous Cell Carcinoma

Squamous cell carcinoma is characterized by its thick, scaly, irregular appearance, but it can have various appearances, and a doctor may be suspicious of any sores on sun-exposed surfaces that do not heal.

Squamous cell carcinoma typically begins as a red area with a scaly, crusted surface. As it grows, the tumor may become somewhat raised and firm, sometimes with a wartlike surface. Eventually, the cancer becomes an open sore and grows into the underlying tissue.

Examples of Squamous Cell Carcinoma

Diagnosis of Squamous Cell Carcinoma

  • Biopsy

When doctors suspect squamous cell carcinoma, they do a biopsy Biopsy Doctors can identify many skin disorders simply by looking at the skin. A full skin examination includes examination of the scalp, nails, and mucous membranes. Sometimes the doctor uses a hand-held... read more Biopsy to differentiate the cancer from similar-looking diseases. In a biopsy, doctors remove a piece of the tumor and examine it under a microscope.

Treatment of Squamous Cell Carcinoma

  • Removal of the tumor (many different methods)

Doctors treat squamous cell carcinoma by scraping and burning the tumor with an electric needle (curettage and electrodesiccation), by cutting the tumor out (surgical excision), by destroying the cancer using extreme cold (cryosurgery), or by applying chemotherapy Chemotherapy and Other Systemic Cancer Treatments Systemic treatments are those that have effects throughout the body rather than being applied directly to the cancer. Chemotherapy is a form of systemic treatment that uses drugs to kill cancer... read more to the skin. Doctors may also use photodynamic therapy (see Using Lasers to Treat Skin Problems Using Lasers to Treat Skin Problems Using Lasers to Treat Skin Problems ), in which chemicals and a laser are applied to the skin, or, occasionally, radiation therapy Radiation Therapy for Cancer Radiation is a form of intense energy generated by a radioactive substance, such as cobalt, or by specialized equipment, such as an atomic particle (linear) accelerator. Radiation preferentially... read more to treat squamous cell carcinoma.

People whose squamous cell carcinomas have returned or are large should be treated with a technique called Mohs microscopically controlled surgery Mohs Microscopically Controlled Surgery Mohs Microscopically Controlled Surgery . Radiation therapy may be done after surgery.

Squamous cell carcinoma that has spread (metastasized) to only one or a few other parts of the body is treated with radiation therapy. If the cancer is widespread, radiation therapy may not be used, and chemotherapy is usually not effective.

People who cannot have surgery and who have large squamous cell carcinomas that have spread to underlying tissue or elsewhere in the body may be given PD-1 inhibitors (such as cemiplimab and pembrolizumab). PD-1 inhibitors help the body's immune system destroy the cancer. These medications are called PD-1 inhibitors because they block the action of a protein on the surface of the cancer cell called programmed cell death protein 1. This protein protects the cancer cell from the effects of the immune system. When PD-1 inhibitors block the protein, the immune system is able to attack the cancer cell and kill it.

Because there is a greater risk of spread with squamous cell carcinoma than with basal cell carcinoma, doctors closely monitor treatment and follow-up.

Prognosis for Squamous Cell Carcinoma

Typically, the prognosis for small tumors that are removed early and adequately is excellent. Treatment is usually effective, and most people survive.

Most squamous cell carcinomas affect only the area around them, penetrating into nearby tissues. However, some spread (metastasize) to distant parts of the body, nearby skin and lymph nodes, and eventually to nearby organs and can be fatal. Tumors that are more than ¾ inch (2 centimeters) in diameter or grow more than 1/8 inch (2 millimeters) deep, or tumors that occur near the ears and lips, in scars, or around nerves are more likely to spread. About one third of cancers on the tongue or elsewhere in the mouth have spread before diagnosis (see Mouth and Throat Cancer Mouth and Throat Cancer Mouth and throat cancers are cancers that originate on the lips, the roof, sides, or floor of the mouth, tongue, tonsils, or back of the throat. Mouth and throat cancers may look like open sores... read more Mouth and Throat Cancer ).

If the cancer is treated before it spreads, the person is usually cured. However, if the cancer has spread, the chance of surviving the next 5 years, even with treatment, is only 34%.

Prevention of Squamous Cell Carcinoma

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

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