Squamous cell carcinoma of the skin, or cutaneous squamous cell carcinoma, is a type of skin cancer that develops when the squamous cells in the top layer of your skin grow out of control. You’ll often find squamous cell carcinoma and basal cell carcinoma lumped together. That’s because they both affect cells in the top layer of the skin.
But there are a couple of key differences between the two types of cancer. Both are often found in areas of your body exposed to sunlight. But squamous cell carcinoma can also develop in areas that don’t get much sun exposure, like the inside of the mouth, palms, soles of the feet and genitals. And with early detection, squamous cell carcinoma is highly treatable. But this cancer can be dangerous in its advanced stages.
According to the Skin Cancer Foundation (SCF), squamous cell carcinoma is diagnosed in more than 1 million people in the U.S. every year, and is responsible for the deaths of more than 15,000 people. The SCF recommends an annual skin exam by a dermatologist, and you may need more frequent screening if you are at higher risk.
Symptoms of squamous cell carcinoma of the skin
It’s important to get anything that looks suspicious checked out. Left untreated, squamous cell carcinomas can invade further into the skin and spread to other parts of the body.
“They can grow extremely quickly and be very dangerous,” said Dr. Amy McMichael, chair of the dermatology department at Wake Forest Baptist Health in North Carolina and a member of the American Academy of Dermatology. “Sometimes if we wait a month, they are too big to remove in the office and you have to go to the operating room.”
If you develop squamous cell carcinoma, you might spot:
- Rough, scaly patches on your skin
- Thickened skin
- Sores that don’t heal properly
- A growth that looks like a wart
- An area with a sunken center
Women are often surprised to find these cancers on their legs. McMichael said women don’t always realize that by wearing shorts, skirts and dresses, their lower legs can be exposed for most of their lives. And once one tumor appears, it’s likely that more will follow. “It’s a hard place to do surgery — there’s not a lot of extra skin there and we don’t want to have to do grafts,” she said.
Causes of squamous cell carcinoma of the skin
The top cause of squamous cell carcinoma of the skin is exposure to ultraviolet radiation from the sun or from indoor tanning. It’s more common in people with light skin, but anyone can develop cutaneous squamous cell carcinoma.
However, people with weakened immune systems — no matter how light or dark their skin is — are at higher risk for developing this type of cancer, said Dr. Ivy Lee, a board-certified dermatologist with Pasadena Premier Dermatology in California and a member of the American Academy of Dermatology.
“[In immunocompromised people] we see it in all different skin types. It’s a wonderful example of how important the immune system is at fighting off precancerous or atypical cells,” she said.
Diagnosing squamous cell carcinoma of the skin
Your doctor may also examine the area with a lighted magnifying lens called a dermascope and feel your lymph nodes to check for signs that the cancer may have spread.
If the potentially dangerous area looks like it could be skin cancer, your dermatologist can remove it in a skin biopsy and send it to a lab for testing.
If you notice something suspicious, your dermatologist will likely ask:
- When it appeared
- How it’s changed
- Whether it’s been painful, itchy or bleeding
- How much UV exposure you’ve had in the past
- What other skin conditions you have
- Whether you have a family history of skin cancer
Treatment for squamous cell carcinoma of the skin
Often, if your doctor removes the entire tumor in the skin biopsy, that’s all the treatment you’ll need for squamous cell skin cancer, according to the American Cancer Society.
If your cancer is more advanced, depending on the size and location of your tumor, your dermatologist might recommend different treatment options.
Squamous cell carcinoma treatment options may include:
- Various types of surgery
- Photodynamic therapy
- Medication you can apply to your skin
You can reduce your risk of squamous cell carcinoma by avoiding indoor tanning and limiting your sun exposure.
The SCF recommends that you:
- Wear clothing that protects your skin
- Stay in the shade, particularly between 10 a.m. and 4 p.m.
- Use a broad-spectrum sunscreen with an SPF of 15 or higher daily
- Use a broad-spectrum, water-resistant sunscreen with an SPF of 30 or higher if you’re going to be out in the sun for an extended time
It’s important to note that while this article focuses on squamous cell carcinoma of the skin. Squamous cell carcinomas can crop up in other parts of the body, such as the mouth or throat. Another type of cancer associated with squamous cells originates in the squamous cells of the lungs and is called squamous cell carcinoma of the lungs.