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Squamous Cell Carcinoma


Gregory L. Wells

, MD, Idaho College of Osteopathic Medicine

Last full review/revision Jan 2021| Content last modified Jan 2021
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 drugs 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 drugs 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, more than a million people are diagnosed with squamous cell carcinoma, and 2,500 die from it.

Squamous cell carcinoma, the second most common type of skin cancer Overview of Skin Cancer Skin cancer is the most common type of cancer. Skin cancer is most common among people who work or play sports outside and among sunbathers. Fair-skinned people are particularly susceptible... read more after basal cell carcinoma Basal Cell Carcinoma Basal cell carcinoma, the most common skin cancer, originates in certain cells of the outer layer of the skin (epidermis). Usually, a small, shiny bump appears on the skin and enlarges slowly... read more Basal Cell Carcinoma , usually develops on sun-exposed areas but may grow anywhere on the skin or in the mouth, where sun exposure is minimal. However, people who have had more sun exposure to their skin have a higher risk of developing squamous cell skin cancer. Fair-skinned people are much more susceptible to squamous cell carcinoma than darker-skinned people.

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

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 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.

Prognosis of 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 2 centimeters in diameter or grow more than 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 metastasized 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 metastasizes, the person is usually cured. However, if the cancer has metastasized, the chance of surviving the next 5 years, even with treatment, is only 34%.

Prevention of Squamous Cell Carcinoma

Treatment of Squamous Cell Carcinoma

  • Removal of the tumor (many different methods)

Squamous cell carcinoma that has spread 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 drugs 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 metastasis than with basal cell carcinoma, doctors closely monitor treatment and follow-up.

More Information

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

See the following sites for comprehensive information about squamous cell carcinoma, including detection, prevention, treatment options, and other resources:

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Test your knowledge
Psoriasis is a common chronic disease affecting 1 to 5% of the population worldwide. It causes distinctive raised, red patches with silvery scales. A border between the patch and normal skin is known as “psoriatic plaque.”  Which of the following is the reason these patches of plaque form?
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