Although squamous cell carcinomas usually develop on sun-exposed skin, they can occur anywhere on your body, including inside your mouth and anus, and on the genitals in both men and women. The appearance of the tumors can vary, but the most common forms include:

• A firm, red nodule on your face, lower lip, ears, neck, hands or arms
• A flat lesion with a scaly crust on your face, ears, neck, hands or arms
• A new ulceration or raised area on a pre-existing scar or ulcer
• An ulcer or flat, white patch inside your mouth
• A red, raised patch or ulcerated sore in the anus or on your genitals

Squamous cell carcinomas are usually slow growing and can be difficult to spot, especially when they appear on skin that has other signs of sun damage, such as changes in pigmentation, loss of elasticity and wrinkling. They can also be mistaken for actinic keratoses — rough, scaly, dark brown or pink patches that appear after years of sun exposure. A small number of actinic keratoses eventually develop into squamous cell carcinomas.

When to see a doctor
Squamous cell carcinomas may be difficult to distinguish from normal skin, especially in the early stages. Yet the sooner they're diagnosed and treated, the better the outcome. See your dermatologist if you have a sore or scab that doesn't heal in about two weeks or a flat patch of scaly skin that won't go away.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Your skin consists of three layers — the epidermis, dermis and subcutis. The epidermis, the topmost layer, is as thin as a pencil line and provides a protective layer of skin cells that your body continually sheds. Squamous cells lie just below the outer surface. Under a microscope, squamous cells in the deeper part of the epidermis resemble bricks; closer to the surface, they look like fish scales.

Basal cells, which produce new skin cells, are at the bottom of the epidermis. Squamous cell carcinomas develop from cells just above the basal layer. They form when cell death and renewal no longer occur as they should. Ordinarily, new cells push older cells toward your skin's surface, and the older cells die and are sloughed off — a process controlled by DNA, your body's genetic material. But if DNA is damaged, this orderly pattern is disrupted, causing cells to grow out of control.

The DNA-UV connection
Most of the damage to DNA in skin cells results from exposure to UV radiation from sunlight and commercial tanning lamps and beds. The damage is cumulative, so the more time you spend in the sun or in a tanning booth, the greater your chance of developing skin cancer. Your risk increases even more if most of your outdoor exposure occurs at times of the day when or in locations where the sun is strongest.

Although sun exposure causes most cases of squamous cell cancinoma, other factors also can lead to this type of cancer, including:

• Therapeutic radiation. Psoralen plus ultraviolet A (PUVA) treatments for psoriasis and X-rays to the head or neck increase your risk of squamous cell carcinoma as well as of melanoma, the most deadly form of skin cancer. It can take years for skin cancers to develop, and many radiation-induced carcinomas that occur later in life may have had their origins in radiation treatments for childhood acne or ringworm. The likelihood that therapeutic radiation will cause cancer depends on a number of factors, including the pigmentation in your skin, the total dose of radiation you receive, and your medical status.
• Chemical toxins. Arsenic, a toxic metal that's found widely in the environment, is a well-known cause of squamous cell carcinoma and other cancers. Though arsenic contaminates the soil, air and groundwater, most people get their greatest exposure in food, especially chicken, beef and fish, and in wine grapes sprayed with arsenic-containing toxins. The Department of Health and Human Services estimates that the average American ingests 11 to 14 milligrams of arsenic every day. Farmers, refinery workers, and people who drink contaminated well water or live near smelting plants are likely to ingest much higher levels.
• Human papillomavirus (HPV). This group of viruses has more than 100 strains, about a third of which are sexually transmitted. Some of the viruses cause genital warts; others can lead to cancer of the vagina, cervix or penis. Now, researchers think that infection with certain types of HPV may also play a role in the development of squamous cell skin cancers.
• Immunosupressant drugs. Up to 80 percent of people who take medications to prevent organ rejection after transplant surgery develop squamous cell carcinoma, though symptoms may not appear for years after surgery. People who have had heart transplants are at greatest risk because they tend to take more drugs at higher doses than do people who have other types of transplants.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Factors that can contribute to squamous cell carcinoma include:

• Chronic sun exposure. A lifetime spent in the sun — or in commercial tanning booths — is the most common cause of squamous cell carcinoma. The threat is greater if you live in a sunny or high-altitude location, both of which expose you to more UV radiation. The risk is also greater if most of your exposure occurred when you were young or you inherit a sensitivity that causes your DNA to sustain more damage than usual from UV light.
• Fair skin. If you have very light skin or freckle or sunburn easily, you're more likely to develop skin cancer than is someone with a darker complexion. Fair-skinned people of Northern European ancestry are particularly at risk. Queensland, Australia, has the highest skin cancer rate in the world because it has unusually high levels of UV radiation and because most of its inhabitants have sensitive English or Irish complexions.
• Your age. Squamous cell carcinoma is more likely to occur in older adults. The average age at which this condition is diagnosed is 66. However, squamous cell carcinoma is occurring with increasing frequency in younger people.
• Your sex. Men are far more likely to develop squamous cell carcinoma than women are, probably because of their greater exposure to the sun.
• A personal history of skin cancer. If you've had squamous cell carcinoma once, you're much more likely to develop it again.
• Weakened immune system. People with weakened immune systems are at greater risk of many diseases, including skin cancer. This includes people who have chronic leukemias, other cancers or HIV/AIDS, and those who have undergone organ transplants or who are, for other reasons, taking medications that suppress the immune system.
• Rare genetic disorder. People with xeroderma pigmentosum, which causes an extreme sensitivity to sunlight, have a greatly increased risk of developing skin cancer because they have little or no ability to repair damage to the skin from ultraviolet light.
• Smoking. Smoking increases your risk of squamous cell carcinoma, and your risk is especially high if you are a current smoker. Although researchers aren't sure why smoking has this effect, they theorize that tobacco damages DNA, making cancerous changes in cells more likely.
• Skin inflammation or injury. You have a slightly higher chance of developing squamous cell carcinoma if you have a large scar, skin infection or an inflammatory skin disease, such as psoriasis.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

When treated early, squamous cell carcinomas generally cause no problems. Although this is uncommon, untreated squamous cell carcinoma can destroy healthy tissue around the tumor, spread to the lymph nodes or other organs, and occasionally prove fatal.

People who have had organ transplants or have chronic lymphocytic leukemia or HIV/AIDS are far more likely to have an aggressive form of squamous cell carcinoma than are people who are otherwise healthy.

Squamous cell carcinomas with the highest risk of complications include:

• Tumors on the lips and ears. Squamous cell carcinomas in these locations are more likely to spread to other sites or recur after treatment.
• Large tumors. Squamous cell carcinomas measuring about 3/4 inch (about 2 centimeters) or more — are also more likely to spread than smaller tumors are.
• Deep tumors. Squamous cell carcinomas that have deeply invaded muscle, cartilage or bone are more likely to recur.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

If you have a skin wound or lesion that concerns you, call your doctor. He or she may recommend that you schedule an appointment with a doctor who specializes in the diagnosis and treatment of skin conditions (dermatologist). In order to ensure a timely examination, be sure to mention when you make your appointment that your doctor has suggested you be evaluated for possible skin cancer.

If you've already had skin cancer, you're at significantly increased risk of a second cancer. Talk with your dermatologist about how often you should be screened for a recurrence. If you have a new wound or lesion that you suspect may be cancerous, schedule an appointment with your dermatologist as soon as possible.

Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

• Write down your medical history, including other conditions for which you've been treated. Be sure to include any radiation therapy you may have received, even years ago.
• Note any personal history that exposed you to excessive UV light, including sunlight or tanning beds. For example, your doctor will be interested to know if you have worked as an outdoor lifeguard or spent lots of time at the beach.
• Make a list of immediate family members who have had skin cancer, to the best of your ability. Skin cancer in a parent, grandparent, aunt, uncle or sibling is all important history to share with your doctor.
• Make a list of your medications and natural remedies. Include any prescription or over-the-counter medications you're taking, as well as all vitamins, supplements or herbal remedies.
• Write down questions to ask your doctor. Creating your list of questions in advance can help you make the most of your time with your doctor.
• Find a family member or friend who can join you for your appointment. Although skin cancer is usually highly treatable, just hearing the word "cancer" can make it difficult for most people to focus on what the doctor says next. Take someone along who can help soak up all the information.

Below are some basic questions to ask your doctor about basal cell carcinoma. If any additional questions occur to you during your visit, don't hesitate to ask.

• Do I have skin cancer? What kind?
• How is this type of skin cancer different from other types?
• Is this type of cancer likely to spread?
• Has my cancer spread?
• What treatment approach do you recommend?
• What are the possible side effects of this treatment?
• Will I have a scar after treatment?
• Am I at risk of this condition recurring?
• Am I at risk of other types of skin cancer?
• How often will I need follow-up visits after I finish treatment?
• Are my family members at risk of skin cancer?
• Are there any brochures or other printed material that I can take home with me? What Web sites do you recommend visiting?

What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to talk about in-depth. Your doctor may ask:

• When did you first notice this skin growth or lesion?
• Has it grown significantly since you first found it?
• Is the growth or lesion painful?
• Do you have any other growths or lesions that concern you?
• Have you had a previous skin cancer?
• Has anyone in your family had skin cancer? What kind?
• How much exposure to the sun or tanning beds did you have as a child?
• How much exposure to the sun or tanning beds do you have now?
• Are you currently taking any medications?
• Are you currently or have you previously used herbal remedies?
• Have you ever received radiation therapy for another medical condition?
• Have you ever taken medications that suppress your immune system?
• What other significant medical conditions have you been treated for, including in your childhood?
• Do you or did you smoke? How much?
• Do you now or have you ever had a job that may have exposed you to pesticides or herbicides?
• Do you now or have you ever relied on well water as your primary water source?
• Do you take precautions to stay safe in the sun, such as avoiding midday sun and using sunscreen?
• Do you examine your own skin on a regular basis?

What you can do in the meantime
In the time leading up to your appointment, talk with family members to find out whether any of your close relatives have been diagnosed or treated for skin cancer, and what kind. This will help your doctor diagnose your condition and plan the most effective treatment and follow-up care plan for you.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

In addition to taking a complete medical history and checking the affected area of skin, your doctor may remove a small skin sample (biopsy) for examination under a microscope. Often, the biopsy is sent to a pathologist who has special expertise in diagnosing skin samples.

A suspected squamous cell carcinoma is often biopsied by shaving off the top layers of skin with a surgical blade. Tumors that have spread deeper into the skin may be partially or completely removed (incisional or excisional biopsy). Because all biopsies are likely to leave a small scar, talk to your doctor about the types of biopsies and their potential for scarring before having the procedure.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Most squamous cell carcinomas can be completely removed with relatively minor surgery or occasionally with a topical medication. The type of squamous cell carcinoma treatment usually depends on the size, location and aggressiveness of the tumor and may include one or more of the following:

• Freezing. This involves removing cancerous cells by freezing them with liquid nitrogen (cryosurgery). It's effective for small squamous cell carcinomas, but isn't recommended for larger tumors or those on your nose, ears or eyelids.
• Simple excision. In this procedure, your doctor cuts out the cancerous tissue and a surrounding margin of healthy skin. Your doctor may recommend a wide excision — removing additional normal skin around the tumor — in some cases. To minimize scarring, especially on your face, consult a doctor skilled in skin reconstruction.
• Laser therapy. An intense beam of light vaporizes growths, usually with little damage to surrounding tissue and with a reduced risk of bleeding, swelling and scarring. Lasers are often used to treat superficial carcinomas on the lips.
• Mohs surgery. This is often considered the most effective treatment for squamous cell carcinomas, especially those that are larger than 2 centimeters, have recurred, or are located on the face, mucous membranes or genital area. During the procedure, your doctor removes the tumor layer by layer, examining each layer under the microscope until no abnormal cells remain. This allows the entire growth to be removed without taking an excessive amount of surrounding healthy skin. Because it requires particular expertise, Mohs surgery should only be performed by doctors specifically trained in the procedure.
• Radiation therapy. This may be an option for treating large cancers on the eyelids, lips and ears — areas that are difficult to treat surgically — or for tumors too deep to cut out.
• Chemotherapy. For very superficial cancers, creams or lotions containing anti-cancer agents may be applied directly to your skin. Some of these medications can cause severe inflammation and scarring, so be sure to discuss potential complications with your doctor.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Most squamous cell carcinomas can be prevented. To protect yourself:

• Avoid the midday sun. Sunlight is strongest between 10 a.m. and 4 p.m., so try to schedule outdoor activities for other times of the day, even in winter or when it's cloudy. You absorb UV radiation year-round, and clouds offer little protection from damaging rays. Keep in mind that sunlight is more intense when it reflects off water, sand and snow.

• Use sunscreen year-round. Sunscreens don't filter out all harmful UV radiation, but they play a major role in an overall sun protection program. Wear a broad-spectrum sunscreen with a sun protection factor (SPF) of at least 15 when you go outside, year-round. Use about 1 ounce (29.5 milliliters) — the amount that fits in the palm of your hand — to cover your entire body, including your lips, ears and the backs of your hands and neck. Apply sunscreen 20 to 30 minutes before sun exposure and reapply it every two hours throughout the day as well as after swimming or exercising.

  A sunscreen called Anthelios SX, which has been widely used in Europe, is now available in the United States. It offers better protection from UVA rays than do traditional broad-spectrum sunscreens and may be more effective in preventing skin cancer.

  Still, don't rely on any sunscreen as your sole means of sun protection. UVA rays penetrate the skin more deeply than UVB rays do and are responsible for skin aging as well as for increasing your risk of cancer.

• Wear protective clothing. Because no sunscreen provides complete protection, it's important to also wear tightly woven clothing that covers your arms and legs and a broad-brimmed hat rather than a baseball cap or visor. Some companies sell photoprotective clothing. Your dermatologist can recommend an appropriate brand. And don't forget sunglasses. Look for those that provide full protection from both UVA and UVB rays.
• Avoid tanning beds. Some tanning salon operators claim that indoor tanning is less damaging than natural sunlight, but the opposite may be true. Tanning beds emit UVA rays, which penetrate deeper into your skin and are more likely to cause cancerous lesions. Some researchers attribute the unusual increase in skin cancers among younger people to the use of tanning beds and sunlamps. If you can't resist the sun-kissed look, choose self-tanning lotions or sprays.
• Be aware of sun-sensitizing medications. Some common prescription and over-the-counter drugs make your skin more sensitive to sunlight. These include antibiotics; certain cholesterol, high blood pressure and diabetes medications; ibuprofen (Advil, Motrin, others); and the acne medication isotretinoin (Accutane). Ask your druggist about the side effects of any medications you take. If they make you more sun sensitive, take extra precautions.
• Perform regular skin checks. Examine your skin often for new growths or changes in existing moles, freckles, bumps and birthmarks. Don't forget to check your scalp, ears, genital area and buttocks.
• Get enough vitamin D. This vitamin may help lower the risk of certain cancers. Although it's normally produced by sunlight on your skin, many experts recommend getting your daily requirement of vitamin D through food or supplements.
• Get your five a day. Studies suggest that a diet rich in fruits and vegetables may lower your risk of cancer, likely due to antioxidant nutrients such as vitamin C, vitamin E and carotenoids. The U.S. Dietary Guidelines recommend that adults following an average diet — about 2,000 calories daily — eat 4.5 cups (nine servings) of fruits and vegetables each day.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.