Basal cell carcinomas usually develop on sun-exposed parts of your body, especially your head and neck. A much smaller number occur on the trunk and legs. Yet basal cell carcinomas can also occur on parts of your body that rarely see the light of day.

Although a general warning sign of skin cancer is a sore that won't heal or that repeatedly bleeds and scabs over, basal cell tumors are likely to take one of these forms:

• A pearly white or waxy bump, often with visible blood vessels on your face, ears or neck. The bump may bleed, develop a crust or form a depression in the center. In darker skinned people, this type of tumor is usually brown or black.
• A flat, scaly, brown or flesh-colored patch on your back or chest. Over time, these patches can grow quite large — up to about 4 to 6 inches (about 10 to 15 centimeters).
• More rarely, a white, waxy scar. This type of basal cell carcinoma is easy to overlook, but it may be a sign of a particularly invasive and disfiguring cancer called morpheaform basal cell carcinoma.

When to see a doctor
Some basal cell carcinomas may be difficult to distinguish from ordinary sores. Yet the sooner they're diagnosed and treated, the better the outcome. See your dermatologist if you have:

• A skin sore that bleeds easily or doesn't heal in about two weeks
• A sore that repeatedly crusts or oozes
• Visible blood vessels in or around a sore
• A scar in an area where you haven't injured yourself

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

Your skin consists of three layers — the epidermis, which is closest to the surface, the dermis and the subcutis. Basal cells, which produce new skin cells, are at the bottom or basal layer of the epidermis. Normally, the new cells push older cells toward the skin's surface, where the old cells die and are sloughed off. This process is controlled by DNA, the body's genetic blueprint. But when DNA is damaged — by solar radiation, for example — the process of cell death and renewal no longer occurs as it should. Instead, cells may grow out of control and eventually form a cancerous tumor.

Environmental factors
As with many other diseases, basal cell carcinomas seem to result from a combination of genetic and environmental factors. Most of the environmental damage to skin cells comes from exposure to UV radiation from sunlight. Although some studies show that the greatest harm occurs during childhood and adolescence, UV damage also appears to be cumulative, so the more time you spend in the sun, the greater your chance of developing skin cancer. Your risk increases even more if most of your outdoor exposure takes place in locales or at times of day when the sun is strongest.

Other environmental factors that can lead to basal cell carcinoma include:

• Therapeutic radiation. Psoralen plus ultraviolet A (PUVA) treatments for psoriasis and X-rays to the head or neck increase your risk of basal cell carcinoma as well as of other, more serious forms 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 basal 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 U.S. 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.
• Immunosupressant drugs. People who take medications to prevent organ rejection after transplant surgery have a greatly increased risk of basal cell carcinoma, though symptoms may not appear for years after the operation.

Genetic factors
Several inherited disorders cause basal cell carcinoma or greatly increase your risk, including:

• Nevoid basal cell carcinoma syndrome (Gorlin's syndrome). People with this rare genetic disorder have numerous basal cell carcinomas as well as pitting on their hands and feet, spine abnormalities, and cataracts.
• Bazex's syndrome. This disorder is marked by numerous basal cell tumors on the face and by a lack of sweating and body hair.
• Xeroderma pigmentosum. People with xeroderma pigmentosum, which causes an extreme sensitivity to sunlight, are at high risk of skin cancer because they have little or no ability to repair damage to the skin from ultraviolet light.

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

Factors that increase your risk of basal cell carcinoma include:

• Chronic sun exposure. A lifetime spent in the sun — or in commercial tanning booths — is the most common cause of basal cell carcinoma. The threat is greater if you live in a sunny or high-altitude climate, both of which expose you to more UV radiation. The risk is also higher if most of your exposure occurred before the age of 18.
• Fair skin. If you have very light skin or you freckle or sunburn easily, you're more likely to develop skin cancer than is someone with a darker complexion. Your risk is greater if you had at least one blistering sunburn in childhood, though sunburns later in life don't seem to increase the risk of basal cell carcinoma.
• Your sex. Men are far more likely to develop basal cell carcinoma than women are, though the incidence in women is increasing.
• Your age. Because basal cell carcinomas often take decades to develop, about 80 percent of basal cell carcinomas occur in people age 50 or older. In recent years, however, the tumors have become much more common in younger people and are increasing every year among adults of all ages.
• A personal or family history of skin cancer. If you've had basal cell carcinoma one or more times, you have a good chance of developing it again. You're also at greater risk if a close relative has had skin cancer.
• Immune-suppressing drugs. Taking medications that suppress your immune system, especially after transplant surgery, significantly increases your risk of skin cancer. Tumors in people with a weakened immune system generally are more aggressive than they are in otherwise healthy people.

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

Basal cell carcinomas that are diagnosed and treated early usually cause no problems. But untreated cancers, especially aggressive morpheaform tumors, can invade and destroy nearby muscles, nerves and bone. One unusual type of basal cell carcinoma — basosquamous — is capable of spreading to other parts of your body.

Basal cell carcinomas are also difficult to eliminate completely. Even after successful treatment, they may recur, often in the same place. Having more than one tumor initially or a tumor on the trunk of your body makes recurrence more likely.

A history of basal cell carcinoma may also increase the chance of developing more serious types of skin cancer, such as squamous cell carcinoma and even malignant melanoma — probably because of long-term sun exposure. Researchers are debating whether having basal cell carcinoma leads to an increased risk of other kinds of cancer.

©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 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?
• 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 basal 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.

A number of therapies exist for treating basal cell carcinoma; the most appropriate one depends on the type, location and severity of the tumor. Some commonly used basal cell carcinoma treatments include:

• Electrodesiccation and curettage (ED and C). This treatment can successfully remove new basal cell carcinomas, but is less effective for recurring tumors. It's often used for tumors located on your trunk, arms or legs. During the procedure, your dermatologist removes the surface of the skin cancer with a scraping instrument (curette) and then sears the base of the tumor with an electric needle.
• Surgical excision. In this procedure, which is used for both new and recurring tumors, your doctor cuts out the cancerous tissue and a surrounding margin of healthy skin. In some cases, you may have a wide excision, which involves removing additional normal skin around the tumor. To minimize scarring, especially on your face, consult a doctor skilled in skin reconstruction.
• Freezing. This involves removing cancerous cells by freezing them with liquid nitrogen (cryosurgery). It's useful for tumors on certain parts of your body and for people with more than one tumor, but it has definite drawbacks, including crusting, slow healing and scarring.
• Mohs' surgery. This is an effective treatment for recurring basal cell carcinomas and those that are large, deep, fast-growing, morpheaform or on your face. 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 tissue. Because it requires particular expertise, Mohs' surgery should only be performed by doctors specifically trained in the procedure.
• Laser surgery. In this relatively new therapy, a laser is used to vaporize superficial basal cell carcinomas. To minimize bleeding, lasers are sometimes used instead of scalpels during surgical excisions.
• Topical treatments. Some superficial basal cell carcinomas are treated with creams or ointments. Tazarotene (Tazorac), a prescription cream normally used for acne, appears to be effective in preventing basal cell tumors. It may have a role in treatment as well, but it hasn't yet been approved for this use, as tests are ongoing. Other, approved topical treatments include imiquimod (Aldara) and 5-fluorouracil. These prescription medications require careful supervision because both can cause severe skin irritation as well as systemic side effects.

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

Most basal 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 your palm — 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.

• 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, or you can research this clothing online. And don't forget sunglasses. Look for a pair that provides full protection from both UVA and UVB rays.
• 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 pharmacist 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, and even your buttocks. If you have had one or more basal cell carcinomas in the past, you and your doctor should be especially vigilant about checking for recurring tumors.
• 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.