Squamous cell carcinoma (SCC) is a type of skin cancer that develops in the outer layer of the skin. It is typically caused by exposure to ultraviolet (UV) radiation from the sun or from tanning beds. SCC can appear as a scaly, red patch, a raised growth with a central depression, or a wart-like growth, and can occur anywhere on the body.

Symptoms of SCC can include a persistent, scaly, or crusted sore; a rough, scaly patch; or a red, inflamed bump that may be tender to the touch. SCC may also bleed or develop a crust over time.

The treatment of SCC depends on the size, location, and severity of cancer. Treatment options may include surgical removal of the cancerous tissue, topical chemotherapy, radiation therapy, or a combination of these approaches.

Prevention of SCC can be done by avoiding prolonged exposure to UV radiation, wearing protective clothing, and using sunscreen with an SPF of at least 30 on exposed skin. Regular skin checks by a healthcare provider can also help detect early signs of skin cancer.

It is important for individuals who notice any changes or abnormalities in their skin to seek medical attention as soon as possible. Early detection and treatment of SCC can improve the chances of a successful outcome.

Squamous cell carcinoma of the skin occurs when the flat, thin squamous cells in the middle and outer layers of your skin develop changes (mutations) in their DNA. A cell's DNA contains the instructions that tell a cell what to do. The mutations tell the squamous cells to grow out of control and to continue living when normal cells would die.

Most of the DNA mutations in skin cells are caused by ultraviolet (UV) radiation found in sunlight and in commercial tanning lamps and tanning beds.

But sun exposure doesn't explain skin cancers that develop on skin not ordinarily exposed to sunlight. This indicates that other factors may contribute to your risk of skin cancer, such as having a condition that weakens your immune system.

Most squamous cell carcinomas of the skin can be prevented. To protect yourself:

• Avoid the sun during the middle of the day. For many people in North America, the sun's rays are strongest between about 10 a.m. and 3 p.m. Schedule outdoor activities for other times of the day, even during winter or when the sky is cloudy.
• Wear sunscreen year-round. Use a broad-spectrum sunscreen with an SPF of at least 30, even on cloudy days. Apply sunscreen generously, and reapply every two hours — or more often if you're swimming or perspiring.
• Wear protective clothing. Cover your skin with dark, tightly woven clothing that covers your arms and legs, and a broad-brimmed hat, which provides more protection than does a baseball cap or visor.
• Some companies also sell protective clothing. A dermatologist can recommend an appropriate brand. Don't forget sunglasses. Look for those that block both types of UV radiation — UVA and UVB rays.
• Avoid tanning beds. Tanning beds emit UV rays and can increase your risk of skin cancer.
• Check your skin regularly and report changes to your doctor. Examine your skin often for new skin growths or changes in existing moles, freckles, bumps and birthmarks. With the help of mirrors, check your face, neck, ears and scalp.
• Examine your chest and trunk and the tops and undersides of your arms and hands. Examine both the front and back of your legs and your feet, including the soles and the spaces between your toes. Also check your genital area and between your buttocks.

Most squamous cell carcinomas of the skin can be completely removed with relatively minor surgery or occasionally with a medicine applied to the skin. Which treatments are best for you depends on the size, location and aggressiveness of the tumor, as well as your own preferences.

Treatments for very small skin cancers

If your skin cancer is very small and has a low risk of spreading, you might consider less invasive treatments, including:

• Curettage and electrodessication (C and E). C and E treatment involves removing the surface of the skin cancer with a scraping instrument (curet) and then searing the base of the cancer with an electric needle. This treatment is often used for small or very superficial squamous cell cancers of the skin.
• Laser therapy. An intense beam of light vaporizes growths, usually with little damage to surrounding tissue and with a reduced risk of bleeding, swelling and scarring. Laser treatment may be an option for very superficial skin lesions.
• Freezing. This treatment involves freezing cancer cells with liquid nitrogen (cryosurgery). It may be an option for treating superficial skin lesions. Freezing might be done after using a scraping instrument (curet) to remove the surface of the skin cancer.
• Photodynamic therapy. Photodynamic therapy combines photosensitizing drugs and light to treat superficial skin cancers. During photodynamic therapy, a liquid drug that makes the cancer cells sensitive to light is applied to the skin. Later, a light that destroys the skin cancer cells is shined on the area.

Treatments for larger skin cancers

More invasive treatments might be recommended for larger squamous cell carcinomas and those that extend deeper into the skin. Options might include:

• Simple excision. In this procedure, your doctor cuts out the cancerous tissue and a surrounding margin of healthy skin. Your doctor may recommend removing additional normal skin around the tumor in some cases (wide excision). To minimize scarring, especially on your face, consult a doctor skilled in skin reconstruction.
• Mohs surgery. During Mohs surgery, your doctor removes the cancer layer by layer, examining each layer under the microscope until no abnormal cells remain. This allows the surgeon to be certain the entire growth is removed and avoid taking an excessive amount of surrounding healthy skin.
• Radiation therapy. Radiation therapy uses high-energy beams, such as X-rays and protons, to kill cancer cells. Radiation therapy is sometimes used after surgery when there is an increased risk that the cancer will return. It might also be an option for people who can't undergo surgery.

Treatments for skin cancer that spreads beyond the skin

When squamous cell carcinoma spreads to other parts of the body, drug treatments might be recommended, including:

• Chemotherapy. Chemotherapy uses powerful drugs to kill cancer cells. If squamous cell carcinoma spreads to the lymph nodes or other parts of the body, chemotherapy can be used alone or in combination with other treatments, such as targeted drug therapy and radiation therapy.
• Targeted drug therapy. Targeted drug treatments focus on specific weaknesses present within cancer cells. By blocking these weaknesses, targeted drug treatments can cause cancer cells to die. Targeted drug therapy is usually combined with chemotherapy.
• Immunotherapy. Immunotherapy is a drug treatment that helps your immune system to fight cancer. Your body's disease-fighting immune system might not attack cancer because the cancer cells produce proteins that blind the immune system cells. Immunotherapy works by interfering with that process. For squamous cell carcinoma of the skin, immunotherapy might be considered when the cancer is advanced and other treatments aren't an option.