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.
(See also Overview 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 .)
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 , 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
Precancerous skin growths caused by previous sun exposure (actinic keratoses Actinic keratoses Sunlight stimulates vitamin D production, helps control some chronic skin diseases (such as psoriasis), and causes a sense of well-being. However, sunlight can cause skin damage. Damage includes... read more )
Chronic sores on the skin or in the mucus membranes (such as those that line the eyes, nose, and lungs) or genitals
Skin that has been scarred, particularly by burns
In the mouth, precancerous skin growths appear as white or red spots (leukoplakia Growths can originate in any type of tissue in and around the mouth, including connective tissues, bone, muscle, and nerve. Growths most commonly form on the Lips Sides of the tongue Floor of... read more or erythroplakia Growths can originate in any type of tissue in and around the mouth, including connective tissues, bone, muscle, and nerve. Growths most commonly form on the Lips Sides of the tongue Floor of... read more ).
Bowen disease Bowen Disease Bowen disease is an early form of squamous cell carcinoma that is confined to the outer layer of the skin (epidermis) and has not yet invaded the deeper layers. (See also Overview of Skin Cancer... read more and possibly keratoacanthomas Keratoacanthomas Keratoacanthomas are round, firm, usually pink or flesh-colored growths that have a central crater that is scaly or crusted. Some keratoacanthomas may be a form of squamous cell carcinoma. ... read more are forms 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.
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 to differentiate the cancer from similar-looking diseases. In a biopsy, doctors remove a piece of the tumor and examine it under a microscope.
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 ).
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%.
Because squamous cell carcinoma can be caused by sun exposure Overview of Sunlight and Skin Damage Sunlight stimulates vitamin D production, helps control some chronic skin diseases (such as psoriasis), and causes a sense of well-being. However, sunlight can cause skin damage. Damage includes... read more , people can help prevent this cancer by doing the following, starting in early childhood:
Avoiding the sun Avoidance Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. Overexposure to ultraviolet light causes sunburn. Sunburn causes painful reddened skin and sometimes blisters, fever... read more : For example, seeking shade, minimizing outdoor activities between 10 AM and 4 PM (when the sun’s rays are strongest), and avoiding sunbathing and the use of tanning beds
Wearing protective clothing Clothing Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. Overexposure to ultraviolet light causes sunburn. Sunburn causes painful reddened skin and sometimes blisters, fever... read more : For example, long-sleeved shirts, pants, and broad-brimmed hats
Using sunscreen Sunscreens Sunburn results from a brief (acute) overexposure to ultraviolet (UV) light. Overexposure to ultraviolet light causes sunburn. Sunburn causes painful reddened skin and sometimes blisters, fever... read more : At least sun protection factor (SPF) 30 with UVA and UVB protection used as directed and reapplied every 2 hours and after swimming or sweating but not used to prolong sun exposure
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 drugs Chemotherapy Chemotherapy involves the use of drugs to destroy cancer cells. Although an ideal drug would destroy cancer cells without harming normal cells, most drugs are not that selective. Instead, drugs... read more to the skin. Doctors may also use photodynamic therapy (see Using Lasers to Treat Skin Problems Using Lasers to Treat Skin Problems Port-wine stains are flat pink, red, or purplish discolorations present at birth due to malformed blood vessels. (See also Overview of Skin Growths and Overview of Growths and Malformations... read more ), 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 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 . Radiation therapy may be done after surgery.
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.
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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