What Is Squamous Cell Carcinoma?

Squamous cell carcinoma (SCC) is a very common type of skin cancer that's linked to sun damage. You can get it anywhere that you have skin. 

Squamous cells are flat cells that make up the outer layer of your skin. Your body constantly sheds old ones and makes new ones. But if these squamous cells mutate and start to build up, a tumor can form.

SCC is a fairly slow-growing skin cancer. When caught early, it’s easy to treat. Unlike some other types of skin cancer, it can spread to your tissues, bones, and nearby lymph nodes over time. If so, treatment can become more complex. 

Squamous cell carcinoma is a common form of skin cancer. It tends to appear on places that are exposed to UV rays like your head, neck, chest, upper back, ears, lips, arms, legs, and hands. (Photo Credit: iStock/Getty Images)

Types of squamous cell carcinoma

Doctors classify SCC based on where it is in your body.

In situ: This means it's only in the top layer of your skin.

Cutaneous: SCC has been found in other layers of your skin.

Metastatic: If you have this type, SCC has spread from your skin to other parts of your body.  While rare, this can happen if SCC isn't found early or goes untreated.

If you sunburn easily, SCC is more likely to show up on parts of your body that have been exposed to ultraviolet (UV) rays from the sun or tanning beds, like your head, neck, chest, upper back, ears, lips, arms, legs, and hands. If you have dark skin, SCC is more likely to be found on other parts of your body that aren't in the sun, like the bottoms of your feet or on your penis or vagina.  

According to the American Academy of Dermatology, SCC can show up as:

A rough, scaly, red patch of skin

An open sore (with or without raised edges)

A brown spot that looks like a typical age spot

A wart-like growth

A very small horn-like growth

A sore growing in an old scar

A smooth or sore reddish-white patch inside your mouth

A red, brown, or black line beneath a nail

A fingernail or toenail that seems to be shrinking

Although SCC is often red or pink, it can also be:

Purple

Gray

Brown or black (or flecked with these colors) 

Yellow

White (if it's inside your mouth)

can also show up differently on different types of skin. For instance:

In Asian Americans, it often appears as a round, raised, brown or black growth.

In African Americans, skin cancer often affects areas that don't get sun, like your palms, feet, lower legs, anus, genitals, or nails.

In Latino or Hispanic people, skin cancer typically starts as a skin growth that keeps getting bigger. Or you could have a scaly patch or notice a dark line under or around a nail.

Sometimes, SCC itches, feels tender to the touch, or feels numb. But early SCC often has no symptoms other than a change in your skin or a sore spot that goes away, then comes back. 

You don't only have squamous cells in the lining of your skin. These special cells are also in many other parts of your body, including inside your mouth and throat. That means that SCC can develop in these areas, too.

Squamous cell carcinoma in the mouth: Your oral cavity includes the inside of your cheeks, your gums, the hard palate (the bony roof of your mouth), underneath your tongue, and behind your wisdom teeth. Almost all cancers found in your mouth are SCC. Because they often don't cause symptoms at first, dentists know to look for SCC during exams.

Squamous cell carcinoma on the tongue:  If you have this type of SCC, you may notice a sore spot or lump on your tongue that doesn't go away. You could also see a thickened area or have some pain or bleeding.

Squamous cell carcinoma on lips: SCC often looks like a cold sore at first. The difference is that it doesn't go away.  If you have fair skin, the sore may appear red. If you're skin is darker, it may look gray or dark brown.

Squamous cell carcinoma in the throat: If SCC grows in the tissues of your larynx (the part of your throat that you use to breathe, speak, and swallow), then you may start to have a sore throat and ear pain.  

Squamous Cell Carcinoma Causes

Being exposed to ultraviolet (UV) rays, like the ones from the sun or indoor tanning beds, is the main cause of SCC. Over time, these rays damage your skin, leading to out-of-control growth of squamous cells, which can then lead to SCC. This is why people who have the greatest risk of developing SCC have less melanin (natural pigment) in their skin, hair, and eyes. 

But it's important to note that anyone can get SCC, even if you never tan or burn in the sun. As much as 65% of all skin cancer in people with dark skin is SCC.

Although UV rays are the primary cause of SCC, many other health conditions, like those that affect your immune system, as well as things you do on a daily basis, can make you more likely to develop SCC.

Factors that can raise your risk of SCC include:

Squamous cell carcinoma in situ: Also called Bowen's disease, squamous cell carcinoma in situ is a pre-invasive squamous cell skin cancer. This means the growth is confined to the outer layer of skin. It should be removed before it spreads and develops into a life-threatening form of skin cancer. SCC is caused by exposure to ultraviolet light. (Photo Credit: Peter Skinner / Science Source)

Your doctor may refer you to a dermatologist who specializes in skin conditions. They will:

If your doctor thinks a bump looks questionable, they’ll remove a sample of the spot (do a skin biopsy) to send to a lab for testing. They could also do an imaging test, like a CT scan or MRI, to see if cancer cells have spread to other parts of your body. 

If SCC is in your mouth or throat, your doctor may also do a procedure called a nasopharyngolaryngoscopy. A very thin, flexible camera is put into your nose to get a more detailed look at structures like your vocal cords and the base of your tongue.

Stages of squamous cell carcinoma

Your test results will help your doctor understand how far cancer cells have spread in your body and which stage the cancer is in. That way, they can find the best treatment for you.

Stage 0 squamous cell carcinoma: This is the earliest stage of SCC. Cancer cells are only in the top layer of your skin.

Stage I squamous cell carcinoma: The cancer is in the top and middle layers of your skin.

Stage II squamous cell carcinoma: Cancer cells are in multiple layers of your skin and around your nerves.

Stage III squamous cell carcinoma: Cancer has been found in your skin and has spread to your lymph nodes.

Stage IV squamous cell carcinoma: This stage means that cancer has spread from your skin to other parts of your body and/or organs.

Squamous cell carcinoma vs. basal cell carcinoma

Although cases of SCC have been climbing for the past 3 decades, basal cell carcinoma(BCC) is still the most common type of cancer. Both types start in the outer layer if your skin, called your epidermis. But SCC affects the upper layer of your epidermis, while BCC affects the lowest (base) layer.

Like SCC, BCC often happens because of damage from UV rays and develops on sun-exposed parts of your body. But unlike SCC, BCC rarely spreads to other parts of your body.

If found early, both BCC and SCC can be removed completely.

SCC can usually be treated with minor surgery that can be done in a doctor’s office or hospital clinic. Depending on the size and location of the tumor, your doctor may choose different techniques to remove it.

For small skin cancers:

For larger skin cancers:

Excision: cutting out the cancer spot and some healthy skin around it, then stitching up the wound

Mohs surgery: excision and then inspecting the excised skin using a microscope; this requires stitching up the wound

Superficial radiation therapy

For cancers that spread beyond your skin:

How long can you wait to treat squamous cell carcinoma?

It's important to treat SCC as soon as possible. When found early, it can be cured. As time goes on, SCC can spread to other parts of your body and become harder to treat.

If it’s not treated, squamous cell carcinoma can spread and damage healthy tissue and organs. In rare cases, it can be life-threatening. That can be more likely if:

To reduce your risk of SCC, try to:

If you’ve been diagnosed with skin cancer, you're more likely to get it again -- so visit your doctor for regular skin checks.

Takeaways

SCC is a common type of skin cancer that anyone can get. Check your skin regularly and follow up with your doctor if you notice any changes or growths. When found early, SCC is very treatable.

What is the survival rate for squamous cell carcinoma?

If a diagnosis is made early and the cancer is treated, the 5-year survival rate is 99%.