Squamous Cell Carcinoma of Skin

Squamous cell carcinoma of the skin is the second most common type of skin cancer, developing when squamous cells in the outer layer of skin grow out of control, most often due to sun exposure.

Table of contents

• What is squamous cell carcinoma?
• Who is affected?
• Symptoms and signs
• What causes squamous cell carcinoma?
• How is it diagnosed?
• Treatment options
• How to prevent squamous cell carcinoma
• Living after treatment

What is squamous cell carcinoma?

Squamous cell carcinoma (SCC) is a type of skin cancer that starts in the top layer of your skin, called the epidermis. It develops when squamous cells, which are flat cells located near the surface of the skin, begin to grow abnormally and out of control^[1][2].

SCC is the second most common form of skin cancer after basal cell carcinoma. Over 1 million people receive a squamous cell carcinoma diagnosis in the United States each year, and the rate has risen about 200% over the past 30 years^[1].

The cancer usually develops in areas of your body that get a lot of sun exposure, such as your face, ears, neck, scalp (if you are bald or have thin hair), forearms, the back of your hands, and lower legs. However, SCC can develop anywhere on your body, including areas that typically receive less sun, such as the genitals^[2][3].

Squamous cell carcinoma can be divided into different types based on how much it has grown or spread. Actinic keratosis represents early skin changes that may turn into SCC if not treated. SCC in situ (also called Bowen’s disease) is an early type where cancer has only grown in the top layer of your skin. Invasive SCC means the cancer has spread into the deeper layers of your skin. Metastatic SCC indicates the cancer has spread to other parts of your body^[3].

Who is affected?

Squamous cell carcinoma can affect anyone, but certain people are at higher risk. You’re most at risk if you have long-term sun exposure or sun damage to your skin at a young age, have a pale complexion with blue or green eyes and blonde or red hair, are 65 years of age or older, have a weak immune system or received an organ transplant, or had chemical exposure such as cigarettes or arsenic^[1].

Males are about two times more likely to develop squamous cell carcinoma than females. People over the age of 50 are most likely to get SCCs, but the incidence has been rising in people younger than 50^[1].

Mortality rates for squamous cell carcinoma are comparable to those of melanoma, renal carcinoma, and oropharyngeal carcinoma in the central and southern regions of the United States^[4].

Symptoms and signs

The first sign of SCC is usually a thick, scaly area on your skin that does not heal. It may bleed or form a sore and tends to grow slowly. As your SCC grows into the deeper layers of your skin, it may grow faster and become painful^[3].

Squamous cell carcinomas can appear in different ways^[2][9]:

• Scaly red patches on the skin
• Open sores that don’t heal or that heal and then come back
• Rough, thickened or wart-like skin
• Raised growths with a central depression or area that sinks down
• A rough-feeling bump or growth that might crust over like a scab and bleed
• An area of skin that’s flat, scaly and red, typically larger than 1 inch (2.5 centimeters)

At times, SCCs may crust over, itch or bleed. If you have SCC in your genital area, it may look like a small sore that doesn’t go away^[2][3].

There are also precancerous signs that can indicate the development of squamous cell carcinoma. These include a bump or lump that can feel dry, itchy, scaly or have a different color from the skin around it, known as actinic keratosis. A lesion on your lower lip where the tissue becomes pale, dry and cracked, called cheilitis, 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 called leukoplakia^[9].

What causes squamous cell carcinoma?

SCC happens when squamous cells in the top layer of your skin grow out of control. This is often caused by too much sun exposure, which damages the skin cells. A mutation to the p53 gene causes squamous cell carcinoma. The most common way that your p53 gene mutates is from ultraviolet (UV) exposure from the sun or from using indoor tanning beds^[1][3].

The p53 gene provides instructions for your cells to divide and replicate to replace cells when they reach the end of their lifespan. Your p53 gene is a tumor suppressor, which means that the gene controls how much and how often your cells divide^[1].

Several risk factors can increase your chances of developing SCC. These include spending a lot of time in the sun, such as working outdoors, having sunspots (solar keratoses), having a weakened immune system, having an HPV (human papillomavirus) infection, and being male^[3].

How is it diagnosed?

Tests and procedures used to diagnose squamous cell carcinoma of the skin include a physical examination and a biopsy. During the physical exam, a member of your healthcare team asks about your health history and looks at your skin for signs of squamous cell carcinoma^[6].

A biopsy is a procedure to remove a sample of tissue for testing in a lab. A member of your healthcare 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^[6].

You should see your doctor if you are worried about skin cancer, notice any changes on your skin, or notice any suspicious spots. It’s important to check your skin regularly, especially if you are at high risk of skin cancer. Look for changes in shape, color, and size of any spots or moles on your skin^[3].

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^[6].

When caught early, most SCCs are curable. Treatment should happen as soon as possible after diagnosis, since more advanced SCCs of the skin are more difficult to treat and can become dangerous, spreading to local lymph nodes, distant tissues, and organs^[8].

Treatments for very small skin cancers

If the skin cancer is small, not deep into the skin, and has a low risk of spreading, less-invasive treatment choices include^[6][8]:

• Curettage and electrodesiccation: This treatment involves removing the top of the skin cancer with a scraping tool called a curet. Then an electric needle is used to sear the base of the cancer.
• Laser therapy: This treatment uses an intense beam of light to destroy growths. There’s usually little damage to nearby tissue and a reduced risk of bleeding, swelling, and scarring.
• Freezing (Cryosurgery): This treatment involves freezing cancer cells with liquid nitrogen.
• Topical medications: Cancer-fighting chemotherapy drugs or immune response modifiers are applied directly to the skin, where they kill off the cancer cells.
• Photodynamic therapy (PDT): A special gel is applied to the affected area that collects in the tumor cells and converts them so that they are very sensitive to certain types of light. This light is then used to destroy the cancer cells.

Surgical treatments

Surgery is usually the first line of treatment and remains the cornerstone of treatment for SCC^[4]. Several surgical procedures can be used^[8]:

• Excisional surgery: Using a scalpel, the surgeon removes the entire tumor along with a “safety margin” of surrounding normal tissue. For small, early SCCs that have not spread, excisional surgery is frequently the only treatment required.
• Mohs surgery: This is considered the gold standard for SCC treatment, especially for lesions on cosmetically sensitive areas like the face, neck, and hands. The surgeon removes the cancer layer by layer while examining each layer under a microscope. This technique ensures all cancerous cells are eliminated while sparing as much healthy tissue as possible, minimizing scarring. Mohs surgery offers the best cure rates, especially for aggressive or recurrent SCC cases.
• Lymph node surgery: Certain skin cancers require the removal of lymph nodes in proximity to cancerous areas.

Additional therapies

Additional therapies may be used following surgery for those with more advanced skin cancer. These include^[14]:

• Radiation therapy: High-energy X-rays or other types of radiation are used to kill cancer cells. Depending on the size and location of the tumor, radiation may be used on its own or to help shrink tumors before moving forward with surgery. This may be recommended for patients who are not good candidates for surgery due to advanced age, health problems, or tumor location.
• Immunotherapy: This type of therapy uses specific medications that stimulate the immune system to fight cancer.
• Chemotherapy: Drugs are used to kill cancer cells or stop them from growing.

Nonsurgical options such as radiation therapy, topical creams, cryotherapy, photodynamic therapy, and laser ablation are available, especially for patients unsuitable for surgery. However, these nonsurgical treatments often have higher recurrence rates^[4].

How to prevent squamous cell carcinoma

Since most skin cancers are linked to sun exposure, it’s important to take precautions when spending time outdoors, no matter what time of year. Too much sun can increase your risk for skin cancer and lead to premature skin aging^[21].

To help protect your skin, you can^[3][19][21]:

• Avoid direct sunlight as much as possible during the peak sun hours, generally 10 a.m. to 3 p.m., or seek shade during this part of the day
• Wear broad-spectrum sunscreen with an SPF of at least 30 containing both UVA and UVB protection. Apply it liberally and reapply regularly, at least every two hours when outdoors, especially if you perspire or have been swimming
• Wear close-weave cotton clothing in the sun, including long sleeves and trousers
• Wear a hat with a wide brim that shades your face and neck
• Wear sunglasses that give 100% UV protection
• Wear lip balm with an SPF 15 or higher
• Never use a sunbed or tanning beds and avoid their UV light

Remember that the sun’s UV rays can reflect off water, sand, concrete, and snow, and can reach below the water’s surface. Certain types of UV light penetrate fog and clouds, so it’s possible to get sunburn even on overcast days^[21].

Regular skin examinations and frequent follow-ups are recommended by healthcare providers, particularly for high-risk patients, to facilitate early detection and treatment^[4]. Be aware of what your skin normally looks like and check your skin regularly to notice changes early^[16].

Living after treatment

Treatment to remove cancer leads to a positive prognosis if the cancer is found and treated early^[1]. However, 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^[16].

Go to see your doctor if you notice any skin changes or possible symptoms of skin cancer. 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^[16].

After treatment, you should continue to practice sun protection measures. Your skin cancer specialist might suggest a high factor sunscreen such as SPF 50 on any exposed skin. The higher SPF gives you extra protection, but no sunscreen can provide 100% protection. For continued protection, you need to reapply sunscreen regularly while in the sun^[16].

If you’re concerned about vitamin D levels while avoiding sun exposure, talk to your skin specialist or doctor about whether you should be taking a vitamin D supplement. You can also get vitamin D from foods including oily fish such as mackerel, sardines and salmon, eggs, red meat, and fortified margarine and cereals^[16].