Squamous Cell Carcinoma

Squamous cell carcinoma is the second most common type of skin cancer, affecting over 1 million people in the U.S. each year. While usually not life-threatening when caught early, understanding this condition and seeking prompt treatment is essential for the best outcome.

Table of contents

• What is Squamous Cell Carcinoma?
• What Causes This Condition?
• Who Is at Risk?
• Signs and Symptoms to Watch For
• Where It Can Occur on Your Body
• How Doctors Diagnose the Condition
• Treatment Options
• How to Protect Your Skin
• Importance of Regular Check-ups

What is Squamous Cell Carcinoma?

Squamous cell carcinoma is a type of cancer that starts as a growth of cells on the skin. It begins in cells called squamous cells, which make up the middle and outer layers of the skin. This is the second most common form of skin cancer after basal cell carcinoma.^[1]

The condition is also known as cutaneous squamous cell carcinoma or CSCC when doctors want to identify it specifically as a skin cancer. This helps distinguish it from squamous cell cancers that can develop inside the body, in places like the mouth, throat, or lungs.^[3]

Cutaneous squamous cell carcinoma, CSCC, SCC of the skin

There are different types of squamous cell carcinoma based on how much the cancer has grown or spread. Early skin changes called actinic keratosis may turn into squamous cell carcinoma if not treated. SCC in situ, also known as Bowen’s disease, is an early type that has only grown in the top layer of skin. Invasive squamous cell carcinoma has spread into the deeper layers of skin, while metastatic squamous cell carcinoma has spread to other parts of the body.^[4]

What Causes This Condition?

A change to a specific gene called the p53 gene causes squamous cell carcinoma. The most common way this gene changes is from ultraviolet (UV) exposure from the sun or from using indoor tanning beds.^[2]

The p53 gene normally provides instructions for your cells to divide and replace themselves when they reach the end of their lifespan. This gene also acts as a tumor suppressor, which means it controls how much and how often your cells divide. When UV radiation damages this gene, the cells can grow out of control and form cancer.^[12]

Most squamous cell carcinomas of the skin are caused by too much ultraviolet radiation. This can come either from sunlight or from tanning beds or lamps. Protecting your skin from UV light can help reduce the risk of squamous cell carcinoma and other forms of skin cancer.^[1]

Who Is at Risk?

Squamous cell carcinoma can affect anyone, but certain people are more at risk. You’re most at risk if you have long-term sun exposure or sun damage to your skin at a young age. People with a pale complexion, blue or green eyes, or blonde or red hair have a higher risk.^[2]

Age is also a factor. People who are 65 years of age or older are more at risk. While people over the age of 50 are most likely to get squamous cell carcinomas, the number of cases has been rising in people younger than 50.^[12]

Other risk factors include having a weakened immune system or having received an organ transplant. People who have had chemical exposure, such as from cigarettes or arsenic, are also at higher risk. Males are about two times more likely to develop squamous cell carcinoma than females.^[2]

If you have sunspots, also called solar keratoses, you may have a higher risk of developing squamous cell carcinoma. An HPV (human papillomavirus) infection can also increase your risk.^[4]

In people with Black and brown skin, squamous cell carcinomas are more likely to be on skin that isn’t exposed to sun, such as the genitals, rather than on sun-exposed areas.^[1]

Signs and Symptoms to Watch For

Squamous cell carcinoma most often occurs on sun-exposed skin, including the scalp, the backs of the hands, the ears, or the lips. The first sign is usually a thick, scaly area on your skin that does not heal. It may bleed or form a sore. It tends to grow slowly at first.^[1]

The condition can appear in several different ways. It may look like scaly red patches, open sores, rough, thickened or wart-like skin, or raised growths with a central depression. At times, squamous cell carcinomas may crust over, itch, or bleed.^[3]

Common symptoms include a rough-feeling bump or growth, which might crust over like a scab and bleed. You might notice a growth that’s higher than the skin around it but sinks down in the middle. Some people have a wound or sore that won’t heal, or a sore that heals and then comes back. An area of skin that’s flat, scaly and red that’s larger, about 1 inch (2.5 centimeters), can also be a sign.^[2]

There are specific warning signs to watch for. A bump or lump that can feel dry, itchy, scaly, or have a different color from the skin around it is called actinic keratosis. A lesion on your lower lip where the tissue becomes pale, dry, and cracked is called cheilitis. This may have a burning sensation when you’re exposed to the sun. White or pale spots in your mouth, on your tongue, gums, or cheeks are known as leukoplakia.^[12]

As squamous cell carcinoma grows into the deeper layers of your skin, it may grow faster and become painful. If not treated, the cancer can grow quickly and spread to other parts of the body.^[4]

Where It Can Occur on Your Body

You can have squamous cell carcinoma on any part of your body. However, it usually grows in areas that get a lot of sun exposure. The most common locations include your face, ears, neck, scalp (if you are bald or have thin hair), forearms and the back of your hands, and lower legs.^[4]

The cancer can also form on your skin in less common areas, including the mouth, tongue and throat, stomach, hands, arms and legs, and anal cavity. It can develop anywhere on the body where you have mucous membranes, which are the inner lining of your organs and body cavities like in your mouth, lungs, and anus.^[2]

• Skin (epidermis)
• Face
• Ears
• Lips
• Scalp
• Neck
• Hands
• Arms
• Legs
• Mouth
• Tongue
• Throat
• Genitals

How Doctors Diagnose the Condition

Diagnosing squamous cell carcinoma usually requires a skin biopsy. While the dermatologist may have a good idea of what a skin abnormality is just by looking at it, the main differences are apparent under a microscope.^[6]

Tests and procedures used to diagnose squamous cell carcinoma of the skin include a physical exam and a biopsy. During the physical exam, a member of your health care team asks about your health history and looks at your skin for signs of squamous cell carcinoma.^[7]

A biopsy is a procedure to remove a sample of tissue for testing in a lab. A member of your health care team uses a tool to cut away, shave off, or punch out some or all of the area of skin that looks unusual. The sample is tested in a lab to see if it is cancer.^[15]

If squamous cell carcinoma has spread to other parts of your body, additional imaging tests or a sentinel lymph node biopsy may be needed. Imaging tests or a physical exam will be done to see which lymph nodes need to be examined.^[5]

Treatment Options

Most squamous cell carcinomas of the skin can be removed with minor surgery. Some are removed with a medicine applied to the skin. The treatment depends on where the cancer is, how large it is, how fast it’s growing, and what you prefer.^[7]

Surgical excision remains the cornerstone of treatment. This procedure involves removing the cancer along with some normal tissue around it, called the surgical margin. It is a common treatment for most types of squamous cell carcinoma. The surgeon uses a scalpel to remove the tumor and some of the surrounding skin to make sure all cancer is eliminated.^[8]

Mohs surgery is considered the gold standard for squamous cell carcinoma treatment, especially for lesions on cosmetically sensitive areas like the face, neck, and hands. This technique involves removing the cancer layer by layer while examining each layer under a microscope. It has the best cure rates, especially for aggressive or recurrent cases. Mohs surgery spares as much healthy tissue as possible, minimizing scarring.^[10]

For very small skin cancers that are not deep into the skin and have a low risk of spreading, less-invasive treatment choices include curettage and electrodessication, laser therapy, and freezing. Curettage and electrodessication involves removing the top of the skin cancer with a scraping tool and then using an electric needle to sear the base of the cancer. Freezing, also called cryosurgery, involves freezing cancer cells with liquid nitrogen.^[15]

Radiation therapy may be recommended for patients who are not good candidates for surgery. This may be due to advanced age, health problems, or tumor location. It involves using high-energy X-rays to target and destroy cancer cells. Radiation therapy is non-invasive with no physical recovery period and is useful for treating hard-to-access tumors.^[10]

For squamous cell carcinoma that has spread to other parts of the body, systemic therapy may be used. This means that the treatment travels through the bloodstream to reach and destroy cancer cells all over the body. Immunotherapy and targeted therapy are some systemic therapies that may be used.^[13]

Other treatment options include photodynamic therapy (PDT) and topical medications. However, these nonsurgical treatments often have higher recurrence rates compared to surgical options.^[5]

Treatment should happen as soon as possible after diagnosis. The sooner you see your doctor and the cancer is diagnosed and treated, the less complicated the surgery to remove it will be, and the faster you will make a complete recovery.^[6]

How to Protect Your Skin

Protecting your skin from UV light can help reduce the risk of squamous cell carcinoma and other forms of skin cancer. To help protect your skin, you can wear close weave cotton clothing in the sun, wear long sleeves and trousers, and wear a hat with a wide brim that shades your face and neck.^[20]

You should wear sunglasses that give 100% UV protection. Apply sunscreen with at least SPF 30 and 4 or 5 stars. Use it generously, reapply regularly, and use together with shade and clothing, even on a cloudy day. Your skin cancer specialist might suggest a high factor sunscreen such as 50 on any exposed skin.^[20]

Spend time in the shade when the sun is strongest, between 11 am and 3 pm in the UK. Never use a sunbed. Using sunscreen does not mean you can safely sunbathe. For continued protection, you need to reapply sunscreen regularly while in the sun.^[20]

When choosing sunscreen, select one with good protection against the 2 main types of ultra-violet (UV) rays – UVA and UVB. This is because both UVA and UVB rays cause skin cancer. The SPF shows how much protection the sunscreen gives against UVB radiation. The higher the SPF number, the more protection it provides. Use a product with at least 4 or 5 stars for UVA protection.^[20]

Regular skin examinations and frequent follow-ups are recommended by healthcare providers, particularly for high-risk patients, to facilitate early detection and treatment. Check your skin regularly to notice changes early.^[5]

Importance of Regular Check-ups

When you’ve had skin cancer, you are more at risk of developing another skin cancer. So it’s important to keep an eye on your skin and protect it when out in the sun. Be aware of what your skin normally looks like. Go to see your doctor if you notice any skin changes or possible symptoms of skin cancer.^[20]

Also see your doctor if there are any changes in the site where you had your original skin cancer. Remember, most non-melanoma skin cancers are treated successfully. It’s rare for early stage skin cancers to come back. So keep an eye on things, but try not to worry too much.^[20]

Every year, people in Australia die from squamous cell carcinomas. However, if not treated, squamous cell carcinoma can grow quickly and spread, and even cause death. Timely surveillance, early diagnosis, and prompt treatment are essential to minimize morbidity and mortality risks.^[4]

Treatment to remove cancer leads to a positive prognosis if the cancer is found and treated early. Although metastasis is rare, the most common site of metastasis is the lymph nodes. While it is more difficult to treat squamous cell carcinoma that has metastasized, up to half of cases can be cured.^[5]

In a small percentage of cases, squamous cell carcinoma can grow along the tiny nerves in the skin. In this very serious condition, the squamous cell carcinoma of the face or scalp can travel along the nerves and spread to the brain.^[6]