Squamous cell cancer (SCC), also known as squamous cell carcinoma, is a type of skin cancer that typically begins in the squamous cells.
Squamous cells are the thin, flat cells that make up the epidermis, or the outermost layer of the skin. (Other parts of the body including the lungs, mucous membranes, and urinary tract also have layers of squamous cells, which may also become cancerous.)
SCC is caused by changes in the DNA of these cells, which cause them to multiply uncontrollably.
According to the Skin Cancer Foundation, cutaneous SCC (SCC of the skin) is the second most common form of skin cancer. Approximately 700,000 people in the United States are diagnosed with this type of skin cancer each year.
People with SCC often develop scaly, red patches, open sores, or warts on their skin. These abnormal growths can develop anywhere, but they’re most often found in areas that receive the most exposure to ultraviolet (UV) radiation, either from sunlight or from tanning beds or lamps.
The condition usually isn’t life threatening, but it can become dangerous if it goes untreated. When treatment isn’t received promptly, the growths can increase in size and spread to other parts of your body, causing serious complications.
Your skin has multiple layers. The outer, protective layer of the skin is known as the epidermis. The epidermis is made up of squamous cells, basal cells, and melanocytes. These cells are constantly shedding to make way for fresh, new skin cells.
However, when certain genetic changes occur in the DNA of any of these cells, skin cancer can occur. The main types of skin cancer are squamous cell carcinoma, basal cell carcinoma, and malignant melanoma.
Squamous cell cancer
Squamous cells are the cells closest to the skin’s surface, and their purpose is to line the skin. SCC often develops on areas of the body that are frequently exposed to UV radiation, such as the face, hands, and ears. In some cases, it can occur in other areas of the body.
Basal cell cancer
Basal cells sit below the squamous cells, and they’re constantly dividing to form new cells. According to the American Cancer Society, basal cell cancer is the most common type of cancer.
Like SCC, basal cell cancer develops on areas exposed to UV rays, particularly the face and neck. This type of cancer tends to grow slowly, and it rarely spreads to other parts of the body.
However, if basal cell cancer goes untreated, it can eventually spread to the bones and other tissues.
Melanocytes are located along with basal cells in the deepest section of the epidermis. These cells are responsible for producing melanin, the pigment that gives skin its color. When cancer develops in the melanocytes, the condition is known as malignant melanoma.
Malignant melanoma is less common than squamous cell and basal cancers, but it’s more likely to grow and spread when it’s left untreated.
SCC often occurs in areas exposed to UV radiation, such as the face, ears, and hands. However, it can also appear in the mouth, in the anal area, and on the genitals.
In its early stages, SCC often presents itself as a scaly, reddish patch of skin. As it progresses, it can turn into a raised bump that continues to grow. The growth may also crust or bleed. In the mouth, this cancer will take on the appearance of a mouth ulcer or a white patch.
In some cases, you’ll notice a new growth on a preexisting scar, mole, or birthmark. Any existing lesions or sores that aren’t healing can also indicate SCC.
Make an appointment with your doctor or dermatologist right away if you notice any of these symptoms. Early diagnosis and treatment are critical for preventing complications.
Skin cancer is caused by mutations that occur in skin cell DNA. These changes cause abnormal cells to multiply out of control. When this occurs in the squamous cells, the condition is known as SCC.
UV radiation is the most common cause of the DNA mutations that lead to skin cancer. UV radiation is found in sunlight as well as in tanning lamps and beds.
While frequent exposure to UV radiation greatly increases your risk of skin cancer, the condition can also develop in people who don’t spend much time in the sun or in tanning beds.
These people may be genetically predisposed to skin cancer, or they may have weakened immune systems that increase their likelihood of getting skin cancer.
Those who have received radiation treatment may also be at greater risk of skin cancer.
Risk factors for SCC include:
- having fair skin
- having light-colored hair and blue, green, or gray eyes
- having long-term exposure to UV radiation
- living in sunny regions or at a high altitude
- having a history of multiple severe sunburns, especially if they occurred early in life
- having a history of being exposed to chemicals, such as arsenic
Your doctor will first perform a physical exam and inspect any abnormal areas for signs of SCC. They’ll also ask you about your medical history. If SCC is suspected, your doctor may decide to take a biopsy to confirm the diagnosis.
A biopsy usually involves removing a very small portion of the affected skin. The skin sample is then sent to a laboratory for testing.
In some cases, your doctor may need to remove a larger part or all of the abnormal growth for testing. Talk to your doctor about any potential scarring or biopsy concerns.
Treatment for SCC varies. Treatment is based on:
- the extent and severity of your cancer
- your age
- your overall health
- the location of the cancer
If SCC is caught early, the condition can usually be successfully treated. It becomes harder to cure once it has spread. Many treatments can be performed as in-office procedures.
- Mohs micrographic surgery. In Mohs surgery, your doctor uses a scalpel to remove the abnormal skin and some of the surrounding tissue. The sample is immediately examined under a microscope. If there are any cancer cells in the sample, the process is repeated until no cancer cells are found.
- Excisional surgery. During excisional surgery, your doctor removes the cancer cells as well as a thin layer of healthy skin in the surrounding area. Stitches are used to close the wound. The sample is then sent to a laboratory to ensure the entire cancerous area has been removed.
- Electrosurgery. Also called curettage and electrodesiccation, electrosurgery involves scraping off the cancer and burning the skin to kill cancer cells. This process is typically done more than once to ensure thorough treatment and complete removal of the cancer.
- Cryosurgery. During cryosurgery, your doctor uses liquid nitrogen to freeze and destroy the cancerous tissue. Like electrosurgery, this treatment is repeated multiple times to make sure all cancerous tissue has been eliminated.
- Radiation. With radiation, high-energy X-rays kill cancer cells. This treatment is administered externally by a machine, which aims the rays at the affected area. Radiation is often performed multiple times a week for several weeks.
Some doctors may also use photodynamic therapy, laser surgery, and topical medications to treat SCC. However, the Food and Drug Administration hasn’t approved these methods for treating SCC:
- Photodynamic therapy. Also known as PDT, this involves the application of a photosensitizing substance to the cancerous areas. After an interval of 1 to 3 hours or longer, the areas that were medicated are exposed to strong light for several minutes. This activates the medication that was applied and kills abnormal cells.
- Laser surgery. Here, a laser removes areas of skin that are abnormal.
- Topical medications. Medications, such as 5-fluorouracil and imiquimod, that are applied on the skin to treat other skin cancers may also help treat SCC.
Once SCC has been treated, it’s critical to attend all follow-up visits with your doctor. SCC can return, and it’s important to monitor your skin for any precancerous or cancerous areas at least once per month.
Early detection of SCC is key to successful treatment. If SCC isn’t treated in its early stages, the cancer may spread to other areas of the body, including the lymph nodes and organs. Once this occurs, the condition can be life threatening.
Those with weakened immune systems due to certain medical conditions, such as HIV, AIDS, or leukemia, have a greater risk of developing more serious forms of SCC.
To help reduce your risk for SCC, follow these tips:
- Limit your sun exposure.
- Avoid the sun during the hottest part of the day, which is between 10 a.m. and 4 p.m.
- Wear sunscreen that has an SPF of at least 30 whenever you go out in the sun.
- Wear sunglasses with UV ray protection.
- Wear a hat and cover your skin when working outside.
- Avoid using tanning beds and lamps.
- Protect your skin during winter as well because winter UV rays can be especially dangerous.
- Check your skin each month for any new or abnormal growths.
- See a dermatologist once per year for a full-body skin check.