Skin cancer is the most commonly occurring type of cancer in the United States. Experts estimate that 40 to 50 percent of Americans who live to age 65 will eventually develop some form of skin cancer. The risk is highest for people who have red or blond hair, light-colored eyes, and fair skin that freckles easily.
The two most common forms of skin cancer are basal cell carcinoma, which accounts for more than 90 percent of all skin cancers, and squamous cell carcinoma. Basal cell carcinoma is a slow-growing cancer, found in the base of the outer layer of skin, that rarely spreads to other parts of the body. Squamous cell carcinoma, which affects cells in the surface of the skin, also spreads infrequently, although it does so much more often than basal cell carcinoma.
A less common type of skin cancer, malignant melanoma, is the most serious form of skin cancer. It spreads quickly and can be fatal. The number of people with melanoma has more than doubled in the United States since about 1980, giving melanoma the fastest-growing incidence rate of all cancers. Melanoma begins in skin cells known as melanocytes, which produce melanin, the pigment
Melanoma is the most serious and dangerous form of skin cancer. It quickly spreads to other parts of the body and can be fatal. The incidence of melanoma is increasing faster than any other type of cancer in the United States. The first sign of melanoma is often a change in the size, shape, color, or feel of an existing mole. Melanoma also can appear as a new black, blue-black, or red-bordered mole. Learn the warning signs of malignant melanoma so you can detect any changes in a mole early. Think of the letters "ABCD" to help you remember what to look for. (For pictures of suspicious moles, see page 92.)
• A—Asymmetry. Half of the mole does not match the other half.
• B—Border. The mole's edges are often ragged, notched, blurred, or irregular in outline. The pigment (color) may spread into the surrounding skin.
• C—Color. The color is typically uneven. Multiple colors—black, brown, tan, gray, red, pink, or blue—may be present.
• D—Diameter. The mole usually increases in size. Melanomas are typically larger than a pencil eraser (half an inch).
Melanomas vary greatly in appearance. Some have all of the above features; others may have only one or two. The most important thing to remember is to tell your doctor about any change you see in a mole as soon as possible so he or she can make a definite diagnosis. When detected and treated early, melanoma can be cured before it has a chance to grow and spread to other parts of the body.
Concerns that gives skin its color. When exposed to the sun, melanocytes produce more 429
pigment, causing the skin to tan. Melanoma occurs when melanocytes become Skin and abnormal and begin to divide without control. The cancer cells then invade sur- Hair rounding tissue and, in some cases, enter the bloodstream or lymph system to spread to other parts of the body. The first sign of melanoma is often a change in an existing mole (see box on previous page). In men, melanoma often appears on the trunk, head, or neck.
The leading cause of all types of skin cancer is excessive exposure to ultraviolet (UV) radiation from the sun, sunlamps, or tanning beds. The cumulative amount of exposure to UV radiation that you have had during your life determines your risk of developing skin cancer—the more exposure, the greater your risk. Most skin cancers appear after age 40, but the sun's damaging effects begin much earlier, in childhood. The most important thing you can do to reduce your risk of skin cancer is to limit the amount of time you spend in the midday sun.
The most common warning sign of skin cancer is a new growth or a sore that does not heal on your skin. The area may look like a small, pale lump or be firm and red. The lump may bleed or develop a crust. Skin cancer also can begin as a flat, red spot that is rough, dry, and scaly. Skin cancer typically appears on parts of the skin—such as the face, neck, hands, and arms—that have been repeatedly exposed to the sun, although it can appear on any part of the body.
Early detection and treatment increase the chances for a cure. That is why it is important to examine your skin regularly for any changes. The best time to perform a skin self-examination is after a shower or bath, using both a full-length mirror and a handheld mirror. Look for anything new—such as a change in a mole or a sore that will not heal. Check all areas of your body, including your face and neck, back, scalp, palms, forearms and upper arms, the backs and fronts of your legs, and your feet. Also check your genitals and the area between your buttocks. Use a comb to part your hair so you can examine your scalp. Examining your skin regularly will help you to become familiar with the normal moles, birthmarks, and blemishes that are present on your skin so you can tell if there is a change in them. Your doctor will check your skin for any "suspicious" growths during a routine physical examination.
Treatment for skin cancer usually involves some form of surgery and, in rare cases, may also require radiation therapy or chemotherapy (treatment with powerful anticancer drugs). Many skin cancers can be cut out of the skin easily in a doctor's office. After numbing the affected area with a local anesthetic, the doctor scoops out the cancer with a spoon-shaped instrument called a curette and then controls bleeding and kills any remaining cancer cells by using an electric current. Most people are left with a flat, white scar. Small skin cancers or precancerous conditions such as actinic keratoses (see page 425) can be treated using cryosurgery, in which the area is frozen with liquid nitrogen and then peeled away. Doctors can use laser treatment on cancer that has affected only the
Concerns outer layer of skin. Laser treatment uses powerful, concentrated beams of light to destroy cancerous tissue.
When a large area of skin has been removed, the person who has been treated for skin cancer may need a skin graft to close the wound and fill in the area of missing tissue. To perform a skin graft, the doctor will take some skin and tissue from another part of the person's body and use it to replace the skin that was removed.
Doctors often use radiation therapy for cancers that appear in areas—such as the eyelid, ear, or tip of the nose—that are difficult to treat with surgery. Radiation therapy is very effective for treating skin cancer, especially in older people, who are less likely to experience any long-term effects. Doctors may treat cancers that are limited to the top layer of skin with creams that contain anticancer drugs such as fluorouracil. Intense inflammation can follow such treatment.
Follow-up care is extremely important because skin cancer can recur in the same general location. About 40 percent of people who have had skin cancer will develop a second skin cancer within 5 years. If you have had skin cancer, examine your skin regularly for any changes, see your doctor for regular checkups, and follow your doctor's instructions about preventing a recurrence. Also remember to stay out of the sun as much as possible.
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