Skin Cancer

Skin cancer — the abnormal growth of skin cells — is the most common form of cancer diagnosed. Doctors diagnose skin cancer in approximately 1 million Americans each year, and about 9,800 Americans die annually of skin cancer.

The three major types of skin cancer are basal cell, squamous cell and melanoma. Basal (BA-sul) cell and squamous (SKWA-mus) cell are the two most common and comprise the large majority of cases of nonmelanoma skin cancer. Both are superficial, slow growing and highly treatable, especially if found early. Melanoma is a more serious form of skin cancer. It affects deeper layers of the skin and has the greatest potential to spread to other tissues in your body.

All three types of skin cancer are on the rise. Fair-skinned people who live in areas that get a lot of sunshine are at greatest risk. But anyone can develop skin cancer, which is most commonly caused by overexposure to ultraviolet (UV) radiation from the sun.

The good news is that most skin cancers are preventable by limiting or avoiding exposure to UV radiation and by detecting changes in your skin at an early stage. If caught early, most skin cancers are highly treatable. For these reasons, it's important to protect your skin from the sun and to check your skin regularly for signs of skin cancer.

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There are three main types of skin cancer:

• Basal cell carcinoma is a nonmelanoma skin cancer and is usually not life-threatening. Basal cell carcinoma is the most common type of skin cancer and accounts for 80% of all nonmelanoma skin cancer.
• Squamous cell carcinoma, also a nonmelanoma skin cancer, is similar to basal cell carcinoma in cell structure and treatment options.
• Melanoma differs from nonmelanoma skin cancer in appearance, cell structure, and treatment options. Melanoma can be life threatening.

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Skin cancer is caused most often by overexposure to the sun and its ultraviolet (UV) rays. Overexposure includes:

• Occasional intense sunlight exposure during childhood that causes severe sunburn and blistering.
• Extensive sunlight exposure over many years.
• Artificial sources of UV radiation, such as tanning beds or sunlamps

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Skin cancer appears as a change in the skin, such as a growth, an irritation or sore that does not heal, or change in a wart or mole. Skin cancer usually affects the head, neck, back, chest, or shoulders.

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A change on your skin is the most common warning sign of skin cancer. Skin cancer may appear as a small growth or as a sore that bleeds, crusts over, heals and then reopens. The first sign of melanoma may be a change in an existing mole or the development of a new, suspicious-looking mole.

Skin cancer develops mainly on areas of skin exposed to a lot of sun, including your scalp, face, lips, ears, neck, chest, arms and hands, and on the legs in women. But skin cancer can also develop on unexposed areas, such as your palms, the spaces between toes and your genital area. A cancerous skin lesion can appear suddenly, or it can develop slowly.

Although skin cancers don't all look the same, they all involve a change in the skin's appearance in a localized area. If you notice any suspicious change in your skin, consult your doctor right away. As with most cancers, early detection increases the chances of successful treatment. Don't wait for the area to start hurting — skin cancer seldom causes pain.

The signs and symptoms of the three most common types of skin cancer are as follows:

Basal Cell Cancer

• A pearly or waxy bump on your face, ears or neck
• A flat, flesh-colored or brown scar-like lesion on your chest or back

Squamous Cell Cancer

• A firm, red nodule on your face, lips, ears, neck, hands or arms
• A flat lesion with a scaly, crusted surface on your face, ears, neck, hands or arms

Melanoma

• A large brownish spot with darker speckles, anywhere on your body
• A simple mole anywhere on your body that changes in color or size or consistency or that bleeds
• A small lesion with an irregular border and red, white, blue or blue-black spots on your trunk or limbs
• Shiny, firm, dome-shaped bumps anywhere on your body
• Dark lesions on your palms, soles, fingertips and toes, or on mucous membranes — skin that lines your mouth, nose, vagina and anus

There are other, less common types of skin cancer. One example is Kaposi's sarcoma, which develops in the blood vessels of your skin. This rare form of skin cancer results in red or purple patches on your skin or on mucous membranes. Like melanoma, it's a serious form of skin cancer. It's mainly seen in people with weakened immune systems, such as those with AIDS or those who've undergone an organ transplant and are taking medications that suppress their immunity. Skin cancer also can develop in any of the other structures of your skin such as the sweat glands, the oil (sebaceous) glands, the erector muscles and the nerves in your skin.

Precancerous skin lesions, such as an actinic keratosis (ak-TIN-ik ker-uh-TO-sis), also can develop into skin cancer. Actinic keratoses appear as rough, scaly, brown-to-dark-pink patches. They're most commonly found on your face, ears, lower arms and hands of fair-skinned people whose skin has been damaged by the sun.

Not all changes in your skin are skin cancer. The only way to get a definitive diagnosis is to see your doctor or dermatologist and have your skin examined.

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These factors may increase your risk of skin cancer:

• Fair skin. Having less pigment (melanin) in your skin provides less protection from damaging UV radiation from the sun or from tanning beds. If you have blond or red hair, light-colored eyes, and you freckle or sunburn easily, you're much more likely to develop skin cancer than is a person with darker features.
• A history of sunburns. A sunburn is your body's attempt to protect itself from the sun's damaging rays. Every time you sunburn your skin, you increase your risk of developing skin cancer. People who've had one or more severe, blistering sunburns as a child or teenager are at increased risk of skin cancer as an adult. Sunburns in adulthood also are a risk factor.
• Excessive sun exposure. Anyone who spends considerable time in the sun may develop skin cancer. This is especially true if your skin is unprotected by sunscreen or clothing. Tanning also puts you at risk. A tan, like a sunburn, is your skin's injury response after excessive UV radiation.
• Sunny or high-altitude climates. People who live in sunny, warm climates are exposed to more sunlight than are people who live in colder climates. People who live at higher elevations, where the sunlight is strongest, also are exposed to more UV radiation than those who live at lower elevations.
• Moles. People who have dysplastic nevi are at increased risk of skin cancer. These moles — which look irregular and are generally larger than normal moles — may be more likely than others to become cancerous. If you have a history of these moles, you and your doctor should watch them regularly for changes. Skin cancer is also more prevalent in people who have a lot of moles.
• Precancerous skin lesions. Having skin lesions known as actinic keratoses can increase your risk of developing skin cancer. These precancerous skin growths typically appear as rough, scaly, brown-to-dark-pink patches. They're most commonly found on the face, lower arms and hands of fair-skinned individuals whose skin has been sun damaged.
• A family history of skin cancer. If your parent or sibling has had skin cancer, you may be at increased risk of the disease.
• A personal history of skin cancer. If you developed skin cancer once, you're at risk of developing it again.
• A weakened immune system. People with weakened immune systems are at a greater risk of developing skin cancer. This may include those who've undergone an organ transplant and are taking medications that suppress their immune systems or people with chronic blood disorders such as leukemia.
• Fragile skin. Skin that has been burned or injured from disease is more susceptible to sun damage and skin cancer. Certain psoriasis treatments can increase the risk of skin cancer.
• Exposure to environmental hazards. Exposure to environmental chemicals, including some herbicides, increases the risk of skin cancer.

Generally, your risk of developing skin cancer increases with age. But skin cancer isn't limited to middle-age and older people. People in there 20s and 30s can develop skin cancer. Signs of skin cancer generally appear after age 50, but the damage to your skin begins much earlier.

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Treatments vary for skin cancers and precancerous skin lesions known as actinic keratoses, which may occur on sun-damaged skin. Treatments depend on the size, type, depth and location of a lesion or lesions. Most treatments use a local anesthetic and can be performed in an outpatient setting. Sometimes no treatment is necessary beyond an initial biopsy that removes the entire growth. If additional treatment is necessary, your options include:

• Freezing. Your doctor may destroy actinic keratoses and some small, early skin cancers by freezing them with liquid nitrogen (cryosurgery). The dead tissue sloughs off when it thaws. The treatment may leave a small, white scar. You may also need a repeat treatment to remove the growth completely.
• Excisional surgery. This type of treatment may be appropriate for any type of skin cancer. Your doctor cuts out (excises) the cancerous tissue and a surrounding margin of healthy skin. A wide excision — taking out extra normal skin around the tumor — may be best for melanoma. To minimize or avoid scarring, especially on your face, you may need to go to a doctor skilled in skin reconstruction.
• Laser therapy. A precise, intense beam of light vaporizes growths, generally with little damage to surrounding tissue and with minimal bleeding, swelling and scarring. A doctor may use this therapy to treat superficial skin cancers or precancerous growths on lips.
• Mohs' surgery. This procedure is for larger, recurring or difficult-to-treat skin cancers, which may include both basal cell and squamous cell cancers. Your doctor removes the skin growth layer by layer, examining each layer under the microscope, until no abnormal cells remain. This treatment is most able to remove skin cancer without taking an excessive amount of surrounding healthy skin.
• Curettage and electrodesiccation. After removing most of a growth, your doctor scrapes away layers of cancer cells using a circular blade (curet). An electric needle destroys any remaining cancer cells. This simple, quick procedure is common in treating small or thin basal cell cancers. It leaves a small, flat, white scar.
• Radiation therapy. Radiation may destroy basal cell and squamous cell skin cancers if surgery isn't an option.
• Chemotherapy. In chemotherapy, drugs are used to kill cancer cells. With skin cancer, chemotherapy can be delivered topically by applying creams or lotions containing anti-cancer agents to the skin. This treatment is useful for cancers limited to the top layer of the skin. An example of an anti-cancer drug applied topically for localized superficial forms of skin cancer or for actinic keratoses is 5 fluorouracil (5-FU).

Treatments for skin cancer under study include:

• Photodynamic therapy. This treatment destroys skin cancer cells with a combination of laser light and drugs that makes cancer cells sensitive to light. Photodynamic therapy for precancerous skin lesions is currently available by prescription.
• Biologic therapy (also called immunotherapy). Interferon and interleukin-2 are under study to treat melanoma and nonmelanoma skin cancers. These immunotherapy drugs stimulate your immune system to fight the cancer. Other medications applied to your skin, such as imiquimod (Aldara), enhance your immune reaction to the presence of skin cancer.

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Most skin cancers are preventable. To best protect your health and skin, take the following steps:

• Limit your time in the sun. Avoid staying in the sun so long that you get a sunburn or a suntan. Both result in skin damage that can increase your risk of developing skin cancer. Sun exposure accumulated over time also may cause skin cancer. In addition to minimizing your time in the sun, set time limits for your child when at the pool or beach. Snow, water and ice all reflect the sun's harmful rays, and UV rays are strongest between 10 a.m. and 4 p.m. Clouds block only a small portion of UV rays.
• Use sunscreen. Before spending time outdoors, apply a broad-spectrum sunscreen with a sun protection factor (SPF) of at least 15. Some sunscreens contain substances that block UVA as well as UVB rays. To identify them, look on the ingredient labels for avobenzone, titanium, dioxide, and transparent or microdispersed zinc oxide. Use sunscreen on all exposed skin, including your lips. Apply sunscreen 30 minutes before sun exposure, and reapply it every few hours or more often if you swim or sweat. Apply sunscreen to infants or young children before going outdoors and teach older children and teens how to use sunscreen to protect themselves. Keep a bottle of sunscreen in your car, your boat, with your gardening tools, and with your sports and camping gear to remind yourself and your family to use it. For extra protection wear tightly woven clothing that covers your arms and legs and a broad-brimmed hat, which provides more protection than a baseball cap or golf visor. You might also consider wearing clothing or outdoor gear specially designed to provide sun protection.
• Avoid tanning beds and tan-accelerating agents. Tanning beds emit UVA rays, which are often touted as less dangerous than UVB rays. But UVA light penetrates deeper into your skin, causes precancerous skin lesions and increases your risk of skin cancer. As for suntan-accelerating products, the Food and Drug Administration warns against their use. Bronzing lotions that produce a tanned look without any sun exposure are a safe choice.
• Check your skin regularly and report changes to your doctor. Examine your skin regularly — monthly if you have had skin cancer, have multiple moles or are at increased risk of skin cancer, and at least every three months otherwise — looking for the development of new skin growths or changes in existing moles, freckles, bumps and birthmarks. With the help of mirrors, check your face, neck, ears and scalp. Examine your chest and trunk, and the tops and undersides of your arms and hands. Examine both the front and the back of your legs, and your feet, including your soles and the spaces between your toes. Also check your genital area and between your buttocks.

To detect melanomas or other skin cancers, use the following A-B-C-D skin self-examination guide, adapted from the American Academy of Dermatology:

• A is for asymmetrical shape. Look for moles with irregular shapes, such as two very different-looking halves.
• B is for irregular border. Look for moles with irregular, notched or scalloped borders — the characteristics of melanomas.
• C is for changes in color. Look for growths that have many colors or an uneven distribution of color.
• D is for diameter. Look for growths that are larger than about 1/4 inch (6 millimeters).

If you have a family history of melanoma and have many moles on your body — especially on your trunk, where you may be less likely to notice changes — consider having regular examinations by a dermatologist. A general guideline for skin examinations is:

• Age 20 to 39: Every three years
• Age 40 or older: Annually

If you've had skin cancer, follow your doctor's advice for a follow-up schedule of examinations.

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For localized melanoma, the 5-year survival rate is 96 percent; survival rates for regional and distant stage diseases are 60 percent and 14 percent, respectively. About 82 percent of melanomas are diagnosed at a localized stage.

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* Text Resources: The Mayo Clinic Staff